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Biology 180 Week 11 Study Questions Autumn 2011 Do these questions with your study group 4 people Follow these rules Everyone must participate in every question that you work on Listen to each person s contributions At least once during each study session each group member should respectfully challenge another member s ideas Assign roles If your group isn t part of a large session at CLUE or Tribeta or the IC one person should serve as timekeeper39 one as organizer keeping people on task and getting a consensus on when to move on to the next question for discussion one as groupdynamics checker making sure everyone is heard one as challenger making sure that all ideas are carefully considered Format 1 Each person should write answers to the first 5 questions individually in 25 minutes or less these questions would be worth about 50 points on an exam Discuss each question 3 minutes each Exchange papers and use the answer key on p3 to grade each other for full credit partial credit or no credit 1 minute each Each member of the group should write 2 exam questions based on key concepts from this week identified in your weekly notes summary Use these questions to quiz each other Do the remaining questions on your own under time pressure about 4 minutes each and discuss with your study group bWN U 1 Consider the pyramid of productivity observed in a wide array of ecosystems What does each level in the pyramid represent What does the width of each level in the pyramid represent Explain why the levels get smaller as you go up the pyramid Draw pyramids from a tropical rainforest versus a desert where the widths ofthe levels are on the same scale Explain why the widths of the levels and the numbers of levels in the two pyramids are the same or different Tropical rainforest Desert 2 Based on data presented in class remember the C and N addition experiments how does high species richness affect global warming and nitrate pollution Explain your reasoning 3 Consider the nitrogen cycle Which box represents the atmosphere NH2 groups in bacteria Plants animals fungi algae Circle a box that is increasing dramatically due to human activities What is this activity Complete the following flow chart explaining why a dead zone is forming in Hood Canal each summer Buildup of NOg39 gt gt H l 4 Why does the conversion of forests to farms and suburbs contribute to increases in atmospheric C02 concentrations 5 In southern Illinois average fitness in a genetically and geographically isolated prairie chicken population was declining over time but then increased dramatically after individuals were introduced from a distant population If the introduction was a onetime event predict the longterm future of the population Explain your reasoning State one way that its longterm future could be improved Answers to questions 15 A trophic level Amount of biomass present Chemical energy in the form of biomass is lost because organisms have to use the energy they gain to do many things besides build biomass including defending themselves maintaining their cells respiration or metabolism transporting fluids digesting inevitable heat loss during reactions etc Tropical rainforest Desert The width of each level and the total number of levels should be higher in the tropics Primary productivity is higher so there is much more biomass available to sustain other trophic levels 2 When C and N concentrations are elevated the amount of biomass produced and thus the amount of C and N taken out ofthe environment increase with increasing species richness Thus high species diversity will mitigate the effects of global warming and nitrate pollution 3 N2 NH2 amino groups due to increased planting of crops that fix nitrogen OR NH3 due to increased use of ammoniabased fertilizers Buildup of N03 Blooms of NOs39using primary producers 02 used up by Fish and other decomposers oxygenusing species die 4 Forests act as carbon sinks because 002 stays locked up in wood for decades or centuries When deforestation occurs the existing wood is often burned or decomposes releasing 002 Farms and suburbs are much less efficient habitats in terms of storing carbon NOs39using primary producers die sink Decomposers bloom 5 Although average fitness improved it would eventually begin to decline if the population stayed small and isolated due to loss of alleles via drift and inbreeding depression Biologists could 1 continue introductions of unrelated individuals andor 2 start other populations nearby so that regular gene flow could occur Additional questions 6 What is net primary production Why does the amount of energy available in an ecosystem decrease with increasing trophic level 7 Fertilizing the open ocean with iron causes dramatic increases in primary productivity by photosynthetic protists and bacteria Suppose that international agencies proposed to conduct massive longterm fertilization of the world39s oceans What are some ofthe possible consequences of such a project 8 How are humans affecting the global nitrogen cycle 9 Why is global warming occurring 10 Suppose you were in charge of managing an endangered population ofturtles in King County Surveys have shown that the few remaining turtles are scattered throughout the county in undeveloped ponds that still have intact marshlands along their edges What steps would you take to make sure that these isolated populations do not become inbred What steps would you take to counteract the effects of genetic drift in the small populations that remain Suppose that money became available to restore turtle habitat by creating ponds on a series of abandoned lots Why would it be important to connect these ponds with culverts grassy strips small streams or other wildlife corridors 11 A radio callin host says that extinction is a natural process and that we should not be overly concerned with loss of biodiversity In response you call in and give the following three reasons for protecting biodiversity 12 Over the past four years the number of bird species that have become threatened with extinction has increased from 168 to 182 If rates of extinction continue at this rate how long will it take for 60 of all bird species to become extinct Approximately 9700 species of birds exist today 13 Consider the genetic problems faced by small populations a Why do small populations become inbred b What are the genetic consequences of inbreeding c What is inbreeding depression d Why is genetic drift a problem in small populations e What is the effect of genetic drift in small populations f Why is loss of genetic variation a problem g If you were managing a small captive population in a 200 how would you counteract these problems 14 Consider the ecological footprint concept State ways to lower Dr Freeman s ecological footprint in each of the following 4 categories and briefly state the logic behind each suggestion Food Transportation Shelter Goodsservices Most individuals find that it would take 46 planets to support their current lifestyle Relate this observation to the concept of carrying capacity 15 39 39 w ulu help 39 39 of biomass that is transferred from primary consumers to secondary consumers eg domestic livestock to peop e 16 Consider climate change a Assess the type of feedback on climate change Event Positive Explanation negativeno High water temperatures trigger bleaching that can kill coral reefs Melting land ice exposes dark rocks b Consider how organisms respond to global warming In each case circle one option Alleles for hightemperature tolerance should increase faster in Shortj wed Longiwed organisms organisms Based on data from the inclass worksheet acclimation will occur more readily in Tropical Northern insects insecm Changes in geographic range area occupied will occur more readily in specieswith seemswim low dispersal high dispersal ability ability aDr Freeman s fatherinlaw worked on phenology seasonal occurrences such as the rst Later swallow to return in spring the rst cardinal ower to B bloom etc His family recorded these data from 19351947 on property they own and then again from 1976present Based on what you know about changes 5 in average global temperature add datapoints and a 1 ical 1 ar l a I Earlier r atyp time and a phenological event 1995 1945 1955 1955 1975 1935 1995 2005 2010 Year In the 1 n quot uie amiiy 39 39 r r haliull But from 1976present his sisterlived on the property and recorded the events What problem does this present in interpreting the data 17 Consider how energy flows through ecosystems a State the relative rank 13 lowhigh of each of the following habitats Hubbard Brook forest in terms of gross photosynthetic efficiency the proportion of incoming Tropical rainforest sunlight that is captured by photosynthesis not NPP Sonora desert Arizona featured in class and the text b In the same ecosystem is it possible for the same amount of biomass to exist in primary consumers and secondary consumers Explain why or why not c Assume that the efficiency of energy transfer from edible corn to edible beef is 10 You have enough corn to feed 100 people an allbeef diet In terms of meeting energy requirements how many people could you feed with the same amount of corn on an allcorn diet 18 Consider data on the number of species currently threatened with extinction N N0 7S r lnA A e N Noequot a Mammals and birds are far and away the beststudied lineages 998 010 r threatened species in 1 2 In terms of the growth rate ofthreatened species which group is in the most trouble Mammals 1096 1141 Birds 1107 1223 b IUCN reported that there were 157 threatened species of amphibians in 2003 and 1770 threatened species of amphibians in 2004 What is the most likely explanation for the difference between the two years 19 In the Amazon rainforest large tracts of contiguous forest are being fragmented Summarize the impact of each of the following processes as natural populations are forced into small geographically isolated populations or Genetic drift Gene flow M utation Answers to additional questions 6 NPR is the amount of new biomass produced by plants and other primary producers per year or other unit of time The amount of energy in trophic levels above primary producers decreases because energy is lost to heat used in basic maintenance of cells cellular respiration stored in indigestible tissues or uneaten and lost tot e decomposer food chain 7 Reductions in the amount of 002 in the atmosphere It is controversial whether enough 002 could be removed to reduce global warming Rapid increases in the amount of organic material that sinks to the ocean bottom Possible development of anaerobic dead zones when this material decays Likely strong effects on marine food webs and food chains because of increase in primary production The consequences of these changes in terms of identity of species that would increase or decrease in response is unknown 8 Humans are adding enormous amounts to selected compartments in the cycle reduced nitrogen in the form of ammoniabased fertilizers or amino groups in nitrogenfixing crops As these compounds are used by species active at other points in the cycle their numbers increase When species that use nitrate explode in numbers and then die their decomposition may use up all available oxygen in aquatic ecosystems and produce dead zones 9 Humans are adding enormous amounts of 002 to the atmosphere through the oxidation burning of fossil fuels Because 002 traps reflected solar radiation it acts as a greenhouse gas Average global temperatures are increasing as a result 10 Transfer turtles from one pond to another Transfer turtles from one pond to another So that turtles could safely migrate from one pond to another This would increase counteract the effects of inbreeding and genetic drift and allow habitats to be recolonized if existing turtles were lost due to some shortterm catastrophe 11 Genetic repository for drugs or other products source of alleles to introduce to domesticated varieties Ecosystem function productivity in many areas increases with species diversity Aesthetics and morality beauty of diverse natural areas and ethical obligation not to extinguish other organisms Direct benefits from healthy fisheries and forests many others are possible including increased resistance to disturbance and invasion increased resilience consult text and lecture notes 12 You need to calculate how long it will take for 60 x 9700 5820 bird species to become extinct if present rates of extinction continue The current rate is calculated as 182 169 A4 Rearranging and solving gives A 1019 and r 0018 If N0 182 then 5820 182 e0 013 Rearranging and solving gives t 1925 years 13 a Even if individuals mate at random in a small population eventually all individuals are related b Frequency of individuals with homozygotes increases c Declines in fitness due to expression of deleterious recessive alleles in homozygotes d Random fluctuations in allele frequencies are more likely in small versus large populations e Leads to random loss or fixation of alleles f lfthe environment changes less variation exists for natural selection to act upon thus the population is less likely to respond to changes in selection g Introduce unrelated individuals as matesparents Food many possible answers logic should make an explicit and speci c connection eg avoid energy losses due to eating primary consumers to reducing the amount of energy required to support his diet eg by eating only or primarily locally produced food Transportation many possible answers logic should make an explicit and speci c connection to reducing the amount of energy required to support movement Shelter many possible answers logic should make an explicit and speci c connection to reducing the amount of energy required to keep him warm and dry eg by increasing ef ciency sharing space Goodsservices many possible answers logic should make an explicit and speci c connection to reducing the amount of energy required There are not enough resources on Earth to support the average American lifestyle for every person living today 15 Almost none ofthe biomass is indigestible eg consisting ofbone or scales or protected by toxins OR The consumers have low metabolic demands so that almost all production is con ed to biomass OR Almost none of he biomass is lost to the decomposer food chain by early death eg illness OR NOTE please be alert for other plausible factors not listed here 16 a High watertemperatures Fewer corals reefs will result in lower NPP which will reduce the trigger bleaching that can Positive amount of CO2 absorbed from the atmosphere and exacerbate kill coral reefs globalwarming Dark rocks absorb more sunlight exacerbating global warming Melting land ice exposes dark Positive rocks b Longrlived Tropical Species with organisms insects low dispersal ability 1 u u m w u E w E m n 1 E 1935 1945 1955 1955 1975 1935 1995 2005 2010 Year There is an ascertainment bias in favor ofthe events are getting earlier hypothesis She is more likely to record events earlier because she is there more 172 3 1 b No there must be loss from one tropic level to another because of energybiomass used for respiration maintenance heat loss generating body heat defense etc c 1000 18 a Mammals 00034 birds 00083 birds are in more trouble b A large research effort concluded between 20032004 so IUCN had much better data 19 Process lmpact4 f or Consequencesimplicationsexplanation no change In small populations drift increases and lead to random loss or fixation of Genetic drift T alleles reducing overall genetic variation Physical separation of occupied habitat will lead to reduced dispersalmovement Gene flow i this is an explanation or Reduced gene flow will lead to divergence of isolated populations this focuses on consequences The size ofthe population has no effect on mutation rate Mutation No change or or With fewer individuals mutation will introduce fewer alleles each generation In small populations inbreeding increases over time as most individuals become Inbreeding T related due to lack of available mates and leads to inbreeding depression Biology 180 Week 2 Study Questions Autumn 2011 Do these questions with your study group N4 people Follow these rules 0 Everyone must participate in every question that you work on 0 Listen to each person s contributions 0 At least once during each study session each group member should challenge another member s ideas 0 Assign roles Ifyour group isn t part of a large session at CLUE or Tribeta or the IC one person should serve as timekeeper one as organizer keeping people on task and getting a consensus on when to move on to the next question for discussion one as groupdynamics checker making sure everyone is heard and respectful one as challenger making sure that all ideas are carefully considered 0 4a God is changing the characteristics of weeds 0 4b When weeds strive to grow in the presence of herbicides their characteristics change in ways that make them better able to grow in this environment They pass these traits on to offspring so the population changes over time 0 4c Weed populations have heritable variation for herbicide resistance Individuals with alleles for resistance produce more offspring than individuals without those alleles As a result the frequency of resistance alleles increases over time Format 1 Each person should write answers to the rst 4 questions on their own in 15 minutes or less these questions would be worth about 30 points on an exam 2 Discuss each question 3 minutes each 3 Exchange papers and use the answer key on p3 to grade each other for full credit partial credit or no credit 1 minute each 4 Read through the rest of the question list Each person should decide which question they want to work on most meaning that they are LEAST confident about 5 Go through the rest of the questions taking turns to decide which to discuss next 6 Each member of the group should write 2 exam questions based on key concepts from this week identified in your weekly notes summary Use these questions to quiz each other 1 Herbicide resistance is currently increasing in many populations of weeds a Under the theory of special creation why are these changes occurring b Under the theory of evolution via inheritance of acquired characters why are these changes occurring c Under the theory of evolution by natural selection why are these changes occurring 2 Consider how evolution by natural selection works a Last fall Dr Freeman posed an exam question that reviewed how HIV populations have evolved in response to antiviral drugs then asked how populations will change in the future The correct answer is It depends on the environment Explain why 100 b An allele called S helps protect humans against Frequency malariaia disease that can be fatalibut has side of 5 effects it can contribute to anemia S alleles are allele common among West African people Graph the frequency of the S allele through time in the descendants of West African people who live 0 in the United States where malaria is NOT present 1600 Present Time 3 Why did the results of Mendel s monohybrid cross con ict with the predictions of Blending inheritance Inheritance of acquired characters 4 In peas letP purple owers and p white owers T terminal owers and t aXial owers A pptt individual crosses with an individual with purple terminal owers 12 of the F1s have purple terminal owers 12 have white terminal owers Was the purple terminal owered parent homozygous or heterozygous at the 2 genes Show your work F1 Punnett square Flower color gene Flower position gene homozygous or heterozygous homozygous or heterozygous Answers to Questions 1 4 la God is changing the characteristics of weeds lb When weeds strive to grow in the presence of herbicides their characteristics change in ways that make them better able to grow in this environment They pass these traits on to offspring so the population changes over time lc Weed populations have heritable variation for herbicide resistance Individuals with alleles for resistance produce more offspring than individuals without those alleles As a result the frequency of resistance alleles increases over time 2 The traits that are favored by natural selection depend on the current environment Thus there is no way to predict what will happen during evolution unless the nature of the environment is known b 100 Frequency ofS allele 1600 present 3 White and purple alleles fo T39me 3 did not blendithe phenotype associated with the white showed up intact in the Fzs White for example showed up in the Fzs but was not acquired in the Rs It would not be possible to observe two different phenotypes in the Fzsinone of the parents had the white ower trait 4 The purple terminal parent s genotype is PiTi where the underscores indicate unknown alleles The genotype of the white terminal offspring is ppTi The pptt parent always contributes a p and a tto this offspring half the time the other parent contributes aP and a T To get 12 white offspring and all terminal offspring then the other parent has to contribute a p half the time and a T all the time PT pT pt Pth pth Flower color gene iheterozygous Flower position gene homozygous Additional questions 5 Early in development human embryos and mouse embryos both have tails Explain why this developmental homology supports the hypothesis that species are related by common ancestry and why it challenges the hypothesis that species were created independently from one another 6 What is the relationship between the quotlaw of successionquot and the observation that similar speciesisuch as the Galapagos mockingbirdsiare found in close geographical proximity 7 Why is the presence of vestigial traits like the human cocch tailbone inconsistent with the theory of special creation also known as intelligent design 8 Compare and contrast the theory of evolution by inheritance of acquired characters with the theory of evolution by natural selection Be sure to analyze both the pattern and the process components of each theory 9 De ne the biological term tness Compare and contrast this de nition with the de nition of tness in everyday English Can tness be measured If so how If not why not 10 De ne the biological term adaptation Give an example Compare and contrast this de nition with the definition of adaptation in everyday English 11 Suppose that you are studying a population of codfish where an average adult female weighs eight pounds Your data indicate that bigger females produce more eggs and leave more offspring than smaller females Based solely on this information indicate on the graph below what is likely to happen to the average weight of females in this population over the next 20 generations 20 Average Weight lbs Ge neration Would you expect that the pattern graphed in part a will continue in perpetuity If so why If not why not Suppose that cod begins to increase in popularity for human consumption In response fishermen begin harvesting most of the largest fish from your study population What effect will this change in the environment have on the average size of a female in this population 12 What evidence inspired Mendel to infer that peas have two alleles for each gene 13 What evidence backed Mendel s claim that hereditary factors genes do not blend together but instead remain intact and independent like particles 14 What is the principle of segregation What data did Mendel use to infer this principle 15 GenesB andR affect eye color in humans Dr Freeman has alleles B R b and r What does the principle of segregation state about the fate of these alleles 16 In cats the Manx allele M causes a short or absent tail while a recessive allele m confers a normal long tail Cats of genotype MM die as embryos If two Manx cats mate what is the probability that each living kitten has a long tail 17 In the plant species Plecm39tz39s congesta individuals produce fruits that either have or do not have prominent structures called wings The alleles involved are W winged fruit WT wingless fruit Researchers collected an array of individuals from the field and performed a series of crosses The results are given in the chart below Complete the chart by writing down the genotype of the parent or parents involved in each cross Write down one genotype if selfing occurs and two genotypes if two different individuals were involved offspring offspring Parental 39 39 wwinged fruits wwingless fruits Parental 39 Wingless selffertilized O 80 winged selffertilized 90 3O winged x Wingless 46 O winged x winged 44 O 18 Caucasians tan in response to exposure to ultraviolet UV radiation Tanning helps protect their skin from the harmful effects of UV exposure Explain why one of the following statements is wrong and why one is right Individuals adapt to habitats with bright sunlight by tanning The ability to tan is an adaptation 19 Define evolution 20 Forest habitats in the Rocky Mountains are becoming drier Suppose that over time the needles of pine trees in the Rockies get shorter and fatteriwhich makes the needles function better under water stress Explain how this could happen under the following theories Lamarckian evolution Evolution by natural selection 21 Explain the following statement Evolution by natural selection is not directed or progressive It just happens In formulating your answer use changes in HIV populations that occur within patients receiving drug therapy as an example Answers to additional questions 5 It is consistent with the hypothesis that humans and mice descended from a common ancestor that had a tail ie the trait is homologous If there were created independently of each other humans shouldn t have a tail because it has no function 6 The law of succession states that species arise from common ancestors in the same geographical area The Galapagos mockingbirds follow the law as they evolved in close proximity from a common ancestor in the islands 7 It is not reasonable to argue that an omnipotent supreme Being or intelligent designer would create organisms with traits that have reduced function or no function unless that Being is thought to be arbitrary and capricious 8 Evolution by inheritance of acquired characters the pattern is that simple organisms are continuously created by spontaneous generation and that over time simpler species evolve into more complex species in a linear fashion The process responsible for this pattern is the inheritance of acquired characters According to this hypothesis changes in traits that occur as a result of effort by an individual are transmitted in the changed form to offspring Evolution by natural selection the pattern is that species are related by descent from a common ancestor and have changed through time The primary process responsible for evolution is natural selection which occurs when heritable differences among individuals cause differences in their reproductive success The key contrasts in the pattern component of the theories are that Lamarkian evolution produces a linear or ladderlike relationship among species whereas evolution by natural selection leads to a bushy or treelike relationship Also Lamarkian evolution is by definition progressive leading from simpler to more complex evolution by natural selection is not necessarily progressive The key contrast in the process component of the theories is that Lamarkian evolution is based on changes that occur in individuals When evolution by natural selection occurs the individuals involved do not change 9 The ability to survive and produce offspring In everyday English fitness means your muscles are toned and your aerobic capacity is good In natural populations fitness can be measured by counting the number of offspring produced by an individual over its lifetime 10 An adaptation is a trait that increases the ability of an individual to survive and reproduce relative to the ability of individuals without the trait Many possible examples In everyday English adaptation means an adjustmentia change in phenotype The change might be in morphology or physiology eg increased blood cell counts in response to a move to high altitude or in behavior 11 20 Average Weight lbs Generation This pattern would not continue forever At some point selection by predators or foodscarcity or some other factor will begin to counteract selection in favor of increased body size Average female size should decrease Alleles that lead to large body size are being selectively removed from the population by a predator 12 Mendel inferred that peas have two alleles for each gene because both versions of the traits that he was studying showed up in the F2 generationifor example purple and white ower color Thus the hereditary factors for both purple and white had to be present in the F1s 13 He never observed intermediate phenotypes and certain traits showed up in their original form in F2 offspring after recessing in the F1 generation 14 The observation that the two alleles present in a parent segregate into different gametes Mendel had to infer that this was correct in order to explain the results of his monohybrid crosses where all F1 offspring were of one phenotype while the F2 offspring we11re a 31 ratio of two phenotypes If the two alleles stayed together these results wouldn t be possible 15 When gametes form the alleles of the two genes will separate to different gametes independently of each other Each gamete gets one allele from each gene and the presence of an allele at one gene doesn t affect which allele is present at the other gene Thus there will be equal numbers of gametes with the genotypes BR Br bR and br 16 13 17 wingless selffertilized 0 80 WTWT winged selffertilized 90 30 WWT winged X wingless 46 0 WW X WTWT winged X winged 44 0 WW X WW or wtwt x wtwi 18 Individuals do not adapt to environmental changesionly populations do The ability to tan is a heritable trait that increases fitness so it qualifies as an adaptation 19 A change in the characteristics of a population over time 20 If pinespruce needles shrink and thicken in response to dry conditions this change would be passed on to offspring As a result the characteristics of the population will change through time Needle shape is atrait with heritable variation If individuals with shorter and fatter needles have higher RS in dry environments than individuals with other types of needles then the characteristics of the population will change over time 21 If a patient starts receiving AZT or another drug HIV particles that happen to be resistant have higher fitness than HIV particles that are not as resistant or that have no resistance to the drug As a result they increase in frequency in the population and evolution by natural selection has occurred or Heritable variation in drug resistance just happensiit does not occur in response to the environment or because HIV particles need it or because they create it somehow Differential RS also just happensiit doesn t happen because it has to for the population to survive or because HIV has to get better or stronger over time Biology 180 Week 5 Study Questions Autumn 2011 Does these questions with your study group 4 people Follow these rules Everyone must participate in every question that you wor on Listen to each person s contributions At least once during each study session each group member should respectfully challenge another member s ideas Assign roles If your group isn t part of a large session at CLUE or Tribeta or the IC one person should serve as timekeeper39 one as organizer keeping people on task and getting a consensus on when to move on to the next question for discussion one as groupdynamics checker making sure everyone is heard one as challenger making sure that all ideas are carefully considered Format 1 Each person should write answers to the first 5 questions on their own in 20 minutes or less these questions would be worth about 40 points on an exam 2 Discuss each question 3 minutes each 3 Exchange papers and use the answer key on p3 to grade each other for full credit partial credit or no credit 1 minute each 4 Each member of the group should write 2 exam questions based on key concepts from this week identified in your weekly notes summary Use these questions to quiz each other 1 Researchers collected data on the fitness of inbred versus outbred offspring in Inbred offspring many populations of the same species juvenile mortality Inbreeding depression is severe in this species but juvenile mortality varies widely among populations Add dots to the graph to predict O the results of this study Each dot represents 0 100 a different population Outbred offspring juvenile mortality 2 Consider the tiny population of Amur leopards remaining in the wild and the proposal to supplement the population with captivereared individuals that are phenotypically distinct 0 Name one genetic problem that the Amur population is probably experiencing and explain why it is occurring 0 What is one drawback of the proposal in terms of the longterm future of the Amur population 0 What is one advantage of the proposal in terms of solving genetic problems in the Amur population 3 This graph shows changes in average beak size Large a heritable trait in the Geospizafonis population n Daphne Major Duringthe 1977 drought G fortis with big beaks survived best because they could crackthe tough fruits of Tribulus cistoides In 2001 however some 6 magnirostris arrived and began breeding on Daphe Majorforthe first time 6 magnirostris have enormous beaks and feed primarily on Tribulus cistoides fruits There was Small another severe drought in 2004 19m 1950 1990 2000 2005 a o u a 9 can a one 9 an 090 9 one 0 Beak size 0 Extend the graph to predict how Gfortis beak size changed in 20042005 0 In the space belowthe graph explain the reasoning behind your prediction 4 Suppose that you are measuring allele frequencies in a population of beetles and notice signi cant changes over a 5year period in the alleles fortwo particular gene One h pothesis is that mutation caused these allele 39equency changes Do you consider this hypothesis likely or unlikely Explain your answer 5 When researchers collected data on cliff swallows that survived a severe winter storm and compared it to the population before the storm t ey found that individuals with larger body size were much more likely to survive individuals The top graph to the right shows the distribution of body size in this population before the storm by the before and alter generations is individuals identical except for the storm Middle graph Plot what the next generation NO genetic would look like ifthere was variation in body size meaning that all observed variation is due to variation in the environment experienced by individuals individuals Bottom graph Plot what the next generation would look like if there is substantial genetic variation in body size Body size grams I Answers to questions 15 2 1 All points should be above the line and the points should range from low juvenile mortality on the left to high onthe ri ht 2 First bullet lnbreeding depression is probably occurring because the population is so small over time all individuals are related R Because the population is so small genetic drift is probably reducing genetic variation Second bullet The alleles that are introduced could have low fitness in the Amur River environment Third bullet The introduction of new alleles could counteract inbreeding depression by making individuals more heterozygous and counter the effects of drift by increasing genetic variation 3 First bullet Should show a spike down at the end ofthe graph Second bullet Beak size should stay the same or decrease because G magnirostris will eat most or all of the Tribuus cistoides fruits With that food source gone there is no selective advantage for G forts with big beaks For full credit articulate environmental changepresence of competition G magnirostris present make logical connection to change in selection on G forts 4 Unless mutation rates andor the number of generations per year are extremely high in this species it is unlikely that mutation caused a measurable amount of allele frequency change in just five years It is much more likely that the change in allele frequencies was caused by natural selection drift or gene flow 5 individuals A individuals individuals Body size grams gt Additional questions 6 Why would evolution eventually grind to a halt if mutation did not occur 3 7 Suppose you are studying a population oleV where drug resistance has increased to high frequency Mll heritable variation continue to exist Mll evolutionary change continue to occur Explain 8 A ock of large ground nches arrived on an island in the Galapagos where this species had not previously occurred The birds stayed and began breeding and thus founded a new population Researchers measured the original arrivals and found that they were signi cantly larger than individuals ofthe same species from the source population Did evolution occur If so what evolutionary force was responsible lfnot why not 9 Why is genetic drift important primarily in small populations 10 lfa large population is suddenly and drastically reduced in size it is said to be undergoing a population bottleneck Genetic dri occurs during bottleneck events because sampling errors occur Explain 11 The data below are from a population of birds native to England In this population is inbreeding bene cial or harmful What observation supports your answer A Number of eggs that law m hatch Dugreenl breeding ow h h 12 Why does inbreeding frequently result in lower survival or vigor in offspring 13 Why isn39t inbreeding considered an evolutionary force 14 In the parental generation suppose that the frequency of A1 is p1 and the frequency of A2 is p2 A2 is recessive A1 is dominant In class you modeled what happens to allele and genotype frequencies when a large number of parents in this population produce gametes and the gametes combine at random to form offspring a Under the conditions you modeled in class what are the genotype frequencies in the offspring generation AA AA A A b Suppose that by chance some of the A1 alleles were converted to A3 alleles Would this affect the result you reported in part a Which assumption of your model is being violated in this case c Suppose that A1A1 parents were more susceptible to a new viral strain than A1A2 or A2A2 parents and produced many fewer offspring State how genotype frequencies observed in the offspring generation would change compared to the result you reported in part a Which assumption of your original model is being violated in this case d When you compare observed genotype frequencies with those expected underthe null model of no evolution and random mating with respect to the gene in question which of the statistical tests that you ve been introduced to in this course is appropriate 15 Fill in the following chart common on on diversity frequencies increasedecreasenonerandom number of alleles present in the population of interest and their relative frequency 16 What is wrong with the statements If populations of human head lice are treated with the insecticide malathion mutations occur that lead to resistance As a result individuals adapt and pass these adaptations on to their offspring 17 Consider mutation a Explain why the following types ofmutation are random A change from a G to a C when DNA is copied during chromosome replication A change in chromosome number due to an error in anaphase ofmeiosis l b Why could a change in quot L 39 quot region of a g r r c Mutation occurs at too low a frequency to be an important factor in changing allele frequencies in one generation Why is mutation a more important evolutionary force in organisms with short generation times Even in organisms with long generation times why is mutation crucial to evolution 18 Recall the experiment we did in class where you simulated making offspring by combining AH and AT alleles at random recorded the resulting genotypes and calculated allele frequencies in the next generation We did two experiments one with a small population and one with a large population Both were carried out for a single generation You can use a computer to do the same experiment with various population sizes continued for many generations The graphs below report results from 6 such experiments Label which results were from a large medium and small population 3 labels total Label all instances where xation or loss occurred Write xation or loss Put a star next to data from one population where the ofheterozygous genotypes remained relatively high I lt 1 as 5 o G G c c in m w D 2 3 a no n 2H m an an we u an an m an mu Generation Ganeration H7 I nu ltlt 5 as E g 01 g I nnv 0 2a m w 3 m Generation 19 The data below are from a small genetically isolated population of bighorn sheep State a hypothesis to explain why average fitness declined from 1920 to 1985 causing the population growth rate to decline In 1985 biologists introduced individuals from a different population Using black dots and a solid line predict the result if the introduced individuals carried alleles that were NOT adaptive in this environment Using open circles and a dashed line predict the result if the introduced individuals solved the problems you identified in part a OJ positive a H U 9 l L U s l 4quot l 3 l e an O c 9 l l 2 a a a a o negative 9 0 19 30 1930 19 50 19 50 19 70 1980 I I I 1990 2000 2010 Year 20 In the spaces provided state the type of statistical test that should be used In each case Go Dawgs Dave Hays is measuring blackberry growth under varied light and soil conditions Before his next experiment he wants to know if the 2 groups of seedlings he ll use are the same height on average even though the 2 groups were planted 72 hours apart Dr Freeman and John Parks are comparing the number of students who fail BiolSO get lt15 vs 215 in 5 quarters each quarter has a different course design 0 Ben Wiggins is testing whether there is a relationship between the final grades that students get in BiolSO and the final grades they get in BioZOO I x A researcher measured the following genotype frequencies A1A1 035 A1A2 036 A2A2 029 ls evolution or nonrandom mating occurring at this gene in this population at this time SHOW YOUR WORK Assume that 5 differences in genotype frequencies are enough to produce a chisquare test with p lt 005 Is your finding more consistent with the hypothesis that A1A1 individuals prefer to mate with other A1A1 individuals the hypothesis that they avoid mating with other A1A1 individuals or that they mate at random Explain 22 Drosophia subobscura feed on fruit and are native to Europe where there is a body size cline smaller individuals are found in warm southern habitats larger individuals are found in cold northern habitats In the early 1980s a small population colonized Chile about a decade later a small population colonized Port Angeles WA where fruit boats from Chile unload At the time of the colonization event were the Chilean and Washington populations like each other and like the European populations Explain Recently Ray Huey s lab Go Dawgs documented that body size clines now exist in Chile and Washington Which evolutionary forces is most likely to be responsible Explain 23 In Lake Erie there is a population of water snakes along the mainland shore and a population on an island snakes can swim back and forth The island has evencolored rocks that the snakes sit on to warm up the mainland does not All snakes in the mainland population have banded coloration many snakes on the island have smooth unbanded coloration When they bask on the island rocks banded snakes are conspicuous and get eaten by hawks much more than smoothcolored snakes Explain why the island population has so many banded snakes 24 You are studying the relationship between hours worked for pay each week and final grade in Biology 180 and do a linear regression analysis What do the following results mean Slope 015 R2018 p 0003 25 Consider prairie chickens They were once abundant in Wisconsin but recently have been reduced to small isolated populations where appropriate habitat remains If you measured genotype frequencies in one ofthese populations what type of departure from HardyWeinberg expectations would occur if inbreeding were occurring Some populations experience inbreeding depression some don t Would these populations be likely to Explain why or why not Suppose wildlife managers are concerned about lack of resistance to a certain nematode parasite One of them claims that resistance alleles are likely to arise by mutation Is this reasonable Explain why or why not 8 Over time how will genetic drift affect these populations Another wildlife manager is proposing to introduce prairie chickens from Nebraska to join individuals in the remaining Wisconsin populations and breed with them What are the pros and cons of this proposal Advantages Disadvantages 26 Consider the phylogeny of mammals 12 pts Which is most closely related to the ancestor of all mammals the monotremes or the bats Which is most closely related to marsupials monotremes or bats Reptiles represent the closest living relatives to today s mammals Add Reptiles to the tree Monotremes lay eggs all other mammals give live birth Map the origin of live birth on the tree Dugongmanatees sealssea lions and whalesdolphins are all aquatic Are the streamlined bodies ofthese animals due to homology or homoplasy Explain your logic Marsupials Golden mole tenrec Elephant shrews Aardvark Elephants Hyraxes Dugong manatees Arm adillos Anteater Sloths Flying shrews tree shrews Prosimians Monkeys Apes Rabbits Rodents Moles Hyenas weasels wolves Seals sea lions PangoHn Horses rhinos Camels pigs cows Hippos whales dolphins ts Answers to additional questions 6 Natural selection and genetic drift tend to eliminate alleles and thus reduce genetic variation in populations If they acted in isolation they would eventually eliminate all genetic variation at many loci and evolution would gr39nd to a haltquot due to a lack of genetic variation This trend is countered by mutation which constantly introduces new alleles and thus genetic variation 7 Mutation will continue to occur and the degree of resistance may continue to increase over time if the same drug continues to be used in the same way timing and dosage Eventually selection on a particular enzyme may be counterbalanced by selection on other aspects oleV s ability to survive and reproduce and change will stop selection will become stabilizing instead of directional Evolution occurred because allele frequencies in the new population are different than they were in the source than F 4 t 43 Au u r a 9 Genetic drift is due to sampling error what we often call luck Deviations from expected 39equencies occur more dramatically in small samples or populations than in large samples or popula ions 10 lfthe reduction is due to a random event like a storm re lava ow or habitat destruction by humans or a glacier meaning that the survivors did not necessarily have higher tness but were simply lucky then allele Ll aa eru Lu u 11 IThe data suggest that inbreeding is harmful The number 39of eggs that fail to hatch is an index of tness In this population hatching failure increases with the degree of inbreeding 12Tworeasons1At quot 39 39 39 39 39 quot quot quot39 quot tness Inbreeding reduces the fre u 39 J 39 will lune ofindividuals in the population 2 If deleterious recessive alleles are present their phenotype will increase in frequency because the frequency homozygous individuals increases under inbreeding Thus the average tness ofindividuals in the population will be lower 13 It only changes genotype frequencies not allele frequencies 1 a p1 2ng p b yes no mutation c too few A1A1 too few A1A2 and too many A2A2 no selection d chisquare test 15 decrease yes increase depends yes random none no none decrease yes decrease increase e random decrease yes increase 16 Must articulate three concepts mutation just happens it does not occur in response to an environmental change individuals don t adapt theyjust have more or fewer offspring changes that occur in individuals are not heritable 17 a l39il Sl DUIIEI 39 quot quot 39 quot 39 4 39 39 wim respect to tnessquot second bullet quotError in replicating mechanicsquot with some indication that you understand that there is a lack of a pattern b If the timing location or amount of expression changes then the activity of gene product and the phenotype nges 39 be a relatively g quot 39 uequency quot39 quot 39 of new alleles 8 Large Small Medium I lt f a 06 a g a E S on g M 5 5 uu a 2a m an an we Generation Generation Generation 19 The data below are from a small genetically isolated population of bighorn sheep 9 pts State a hypothesis to explain why average fitness declined from 1920 to 1985 causing the population growth rate to decline Inbreeding depression is occurring OR Genetic drift has decreased allelic variation at genes that are important to fitness In 1985 biologists introduced individuals from a different population Using black dots and a solid line predict the result ifthe introduced individuals carried alleles that were NOT adaptive in this environment Using open circles and a dashed line predict the result ifthe introduced individuals solved the problems you identified in part a l cu positive l 4 m a o g a a a i o a no lo ED 0 O c l i o g a g M O U G W o 3 a W 0 g l 1 l negative 9 l 0 19 30 19 40 19 50 19 50 19 70 1980 I 1990 2000 2010 Year 20 ttest chisquare test linear regression 21 frA1 053 frA2 047 If genotypes are at HW proportions then A1A1 028 39 049 A2A2 022 Yes either evolution or nonrandom mating or both are occurring They prefer other A1A1 individuals There are too many A1A1 individuals observed given the allele frequencies suggesting that they don t mate at random and prefer like genotypes 22 No because the populations were small they are likely to be highly distinct due to genetic drift Specifically allele frequencies would differ and overall genetic variation would be lower Selection The cline in Europe suggests that large body size is advantageous in cold habitats while small body size is advantageous in warm habitats The most likely explanation of the patterns in Chile and Washington are that temperature variation existed from north to south and that over time selection sorted individuals out by size 23 Gene flow in the form of snakes that swim to the island from the mainland regularly introduces alleles for banded coloration even though selection is removing them 24 As hours worked for pay increase final grade in Biology 180 decreases Variation in hours worked for pay each week explains 1827 of the variation in final grade By chance there is only a 0307 probability of seeing a relationship this strong between hours worked for pay and final grade 25 Too many homozygotes observed compared to the expected number under HardyWeinberg Yes because the population has only been small for a short time meaning that a significant number of deleterious alleles are likely to be present No on a per gene basis mutation is much too slow to make this likely and the population size is too small to make it likely that even a single individual will get a beneficial mutation In addition most mutations are deleterious Advantages Can introduce new alleles that limit the effects of inbreeding depression and that may be beneficial in this environment for example by offsetting the effects of loss of genetic variation Disadvantages Can introduce alleles that are not well adapted to this environment reducing average fitness 26 Neitherequal Bats Homoplasy If the trait were homologous then the common ancestor of these species would have to have streamlined bodies and most or all of its descendants should share the trait But few do meaning that it would have to be lost many times It is more parsimonius to conclude that the trait arose independently in the three lineages Live birth Reptiles Marsupials Golden mole tenrec Elephant shrews s Dugong manatees Arm adillos Anteater Sloths Flying shrews tree shrews Prosimians Monkeys pes Rabbits Rodents Moles Hyenas weasels wolves Seals sea lions PangoHn Horses rhinos Camels pigs cows Hippos whales dolphins Bats Biology 180 Week 7 Study Questions Autumn 2011 Does these questions with your study group 4 people Follow these rules Everyone must participate in every question that you work on Listen to each person 5 contributions At least once during each study session each group member should respectfully challenge another member s ideas Assign roles If your group isn t part of a large session at CLUE or Tribeta or the IC one person should serve as timekeeper39 one as organizer keeping people on task and getting a consensus on when to move on to the next question for discussion one as groupdynamics checker making sure everyone is heard one as challenger making sure that all ideas are carefully considered Format 1 Each person should write answers to the first 5 questions on their own in 20 minutes or less these questions would be worth about 40 points on an exam 2 Discuss each question 3 minutes each 3 Exchange papers and use the answer key on p3 to grade each other for full credit partial credit or no credit 1 minute each 4 Each member of the group should write 2 exam questions based on key concepts from this week identified in your weekly notes summary Use these questions to quiz each other 1 Several lines of evidence suggest that a 10km wide asteroid hit the Earth about 65 million years ago Which piece of evidence do you find most convincing and why Why would the impact event have resulted in the extinction of large numbers of species Which region ofthe world should have experienced the highest extinction rates and why 2 a State a hypothesis to explain the adaptive significance of the following traits and map them on the tree Chara Pellen Liverworts Mosses Hornworts Lycophyta Embryophyte condition Horsetans Ferns GGym nosperms Cuticle Angiosperms b How would you test your hypothesis about cuticle Assume that you have some mutant moss where cuticle does not form 3 a State the adaptive significance of the following traits Bilateral symmetry Coelom Epithelial skin tissue b How would you test your hypothesis about epithelium Assume you have some mutant sponges where epithelium does not form 4 Consider the evolution of land plants Vessels evolved in gnetophytes and angiosperms lf researchers were able to identify the genes responsible for vessel formation in both groups state the predictions made by the following hypotheses Angiosperm and gnetophyte vessels are homologous Angiosperm and gnetophyte vessels are an example of homoplasy Is it appropriate to call the liverworts hornworts and mosses lower plants Explain why or why not 5 Name two the defining features of chordates and explain their adaptive significance Answers to questions 15 1 Several answers are possible see the text Most biologists consider the crater the most convincing evidence because it is difficult to propose a reasonable alternative hypothesis for how it could have formed if an impact hadn t occurred Evidence in the fossil record indicates that a huge tsunami occurred along with widespread forest fires and possibly extensive volcanism In addition a huge quantity of sulfurladen particles would have been released to the atmosphere at the impact site Dramatic global cooling would have resulted North America because it was in the splash zone near the impact site Embryophyte condition Cuticle C Pollen Sperm are better protected OR Sperm are more likely to reach the egg Offspring can be nourished by parent OR Offspring can be protected by parent Reduce water loss from tissues exposed to air Grow mutant and normal moss of the same species under identical conditions eg soil watering light nutrients provided including at least some intervals where air is dry Compare spore production gamete production growth rate lifespan or some other measure of fitness 3 Bilateral symmetry organize body into distinctive headtail regions OR makes tubewithinatubedesign possible OR face environment in one direction Coelom provide cavity where internal organs can be arranged and organized OR provide fluidfilled cavity that can function as a hydrostatic skeleton Epithelial skin tissue protection from predators disease or mechanical damage OR reduce or eliminate loss of nutrients from interior cells OR regulate exchange of molecules across body surface Grow mutant and normal sponges under identical physical conditions salinity temperature light water depth crowding then expose them to an agent appropriate to the hypothesis being tested eg a fish predator if the adaptive advantage is proposed to be protection from predators Measure and compare growth rate production of gametes or larvae or other aspect of fitness 4 The genes involved are homologous the same The genes involved are different not homologous No evolution is not progressive so they are not lower in any meaningful sense They simply evolved earlier have been around longer 5 Dorsal nerve cord coordinate movement Pharyngeal gill slits used in filter feeding and gas exchange Muscular postanal tail used to power swimming movements Notochord provides a simple endoskeleton used in movement Additional questions 6 Researchers initially hypothesized that all human evolution was anagenetic meaning that a single population had changed through time from the common ancestor of chimps and humans to Homo sapiens What evidence suggested that this hypothesis was not correct 7 What trends occurred over the past five million years of human evolution For each trend state a hypothesis for why the observed change might have been adaptive in the environments occupied by our ancestors 8 If you make a logarithmic plot of overall body size versus brain size for mammals the data points fall on a straight line The data points for fossil and living humans however fall far above this line What does this observation mean 9 Suppose that you are a scientist from outer space and have just encountered Homo sapiens Write a scientific description of our species Stated anotherway what distinctive characteristics identify this species 10 What evidence suggests that hominins in the genus Paranthropus occupied a distinct niche from species of Austraopithecus andor Homo that lived at about the same time in the same region 11 Name a plant lineage that you would expect to find in relatively moist environments Explain why 12 Name a plant lineage that you would expect to find in relatively dry environments Explain why 13 In the forests of eastern North America a plant called bracken fern has been increasing dramatically recently Deer cannot eat bracken fern State a hypothesis to explain why bracken fern is increasing Outline an experiment that would test your hypothesis Hypothesis Experimental design 14 The text reviews experiments on orchid populations with differing spur lengths and pollinators In these experiments why was it significant that handpollinated plants set much more seed than naturally pollinated plants 15 Recall that a large PR attachment surface for gaping muscles is hypothesized to be a morphological innovation that triggered the adaptive radiation of blackbirds But some blackbirds do not gape to find food and have tiny PRs Provide an interpretation for each of the following scenarios The tiny PR species are the earliest lineages to branch off on the phylogeny of blackbirds The tiny PR species are a highly derived group that appear late in the adaptive radiation of blackbirds 16 Considerthe graph to the right there are 3 regression lines 1500 What is the dependent response variable 1300 What is the independent predictor variable Braincase 100 volume 900 Is the choice of dependent and independent variables correct here Why or why not 700 500 g ustmlopith ecu Exta nt great a pas 300 30 50 70 90 110 What conclusions can you draw from this graph Body Mass kg 17 Consider a major evolutionary innovation vascular tissue in plants The fossil record indicates that early in land plant evolution there were five types of waterconducting cells All have a primary 1 cell wall some have a secondary 2 cell wall that makes vascular tissue stronger much stronger if it is extensive Perforations are partial gaps in cell walls that help water move between cells pits are complete gaps holes in cell walls that allow water to move between cells in vascular tissue much more easily with highest efficiency Vascular tissue 2 cell wall quot 39 or pits Species A Yes Extensive continuous sheet Pits Species B Yes Extensive continuous sheet Perforations Species C No simple cells No Neither Species D Yes Small amount in simple rings Neither Species E Yes Moderate amount in rings Neither Species F is closely related but lacks any type of waterconducting cells or tissue Assume that vascular tissue evolved from simple types to morecomplex types aPredict the phylogeny b Predict the position of species c Predict the date of first put a letter at each tip AF in the geologic record appearance of species AF via radiometric dating absolute age shallower rocks M more recent V youngest N W W Deep oldest er rocks more ancient quot d Predict whether structural similarity between the 2 cell wall material in species A and the 2 cell wall material in species D is due to homology or homoplasy 18 Consider adaptations that allowed plants to thrive on land Prior to the evolution of the embryophyte condition fertilized eggs simply dropped off the parent plant and dispersed Explain how the lack of quotfertilizedeggretention limited fitness Prior to the evolution of stomata pores allowed gas exchange across an epidermis that was covered in cuticle Explain how the presence of pores rather than stomata limited fitness 19 Consider the evolution and diversification of animals a Given the information in the chart map and label the origin of the following 6 traits on the tree provided 5 a E E z E E 2 a E 3 u g o 0 E g 13 g E E g o 5 Outgroup 4 0 33 7 5 E quot g E o o b o m gt L a 0 Lu Lu Lu u n m n 1 z Sponges Jellyfish et al Comb jellies Acoels Rotifers Flatworms Annelids Mollusks Rou ndworms Arthropods Echinoderms Chordates b Recent work suggests that sponges are paraphyletic Add a group called quotSponges2quot to the tree to reflect this observation c Circle the monophyletic group called quotcoelomatesquot animals with a coelom d What is the sister group to the coelomates 20 State a hypothesis to explain the adaptive significance of the jaw in the earliest jawed vertebrates when the structure consisted of two simple rods above and below the mouth Answers to additional questions 6The existence of several hominin species in the same geographic regions at the same time 7 Increased brain size increased memory and learning ability used to manufacture tools and manage social interactions Smaller teeth and jaws Improved ability to speak relaxed selection for ability to process coarse foods because of tool and fire use Increased height Improved ability to hunt andor fight Reduced sexual size dimorphism produced by relaxed sexual selection due to increased paternal care Increased cultural evolution rapid spread of ideas relating to tool use hunting or agricultural strategies religious beliefs politicalsocial systems 8 For their body size hominins have extraordinarily large brains 9 A bipedal primate with an extraordinarily large brain relative to body size Low degree of sexual size dimorphism largely monogamous mating system with intensive maternal and paternal care of offspring Little fur Extremely well developed capacity for cultural evolution 10 The three species of Paranthropus known in the fossil record had traits such as large zygomatic arches sagittal crests andor extremely large molars that support the hypothesis that they fed on nuts and other coarse hardtoprocess foods These traits are not found in Austraopithecus or Homo which presumably fed on very different types of food 11 Species with sperm that must swim to egg Water must be present for fertilization to occur 12 Species that produce pollen because fertilization is not dependent on the presence of water 13 Hypothesis Deer are increasing in numbers and are eating plants that compete with bracken fern for sunlight water space and other resources Experimental design In a forest where deer are abundant carefully quantify the number and identity of plants present in a large number of experimental plots Then erect deerproof fences around half of these plots Ifthe hypothesis is correct bracken fern should thrive in the nonfenced plots but begin to decline inside the fenced plots 14 It is consistent with the hypothesis that these species are pollenIimited meaning that the fitness of individuals is limited by their ability to attract pollinators and have their pollen transferred to other individuals In species where this is the case there should be intense selection for traits that increase the attractiveness of flowers to pollinators 15 The earliest blackbirds lacked a large PR they retained the ancestral state A large PR did not evolve at the base ofthe monophyletic group but later A large PR evolved early in the radiation but was lost in one or more lineages 16 Braincase volume body mass Yes braincase size should depend on overall body size not the other way around Species of Homo have much larger brains relative to overall body size than species of Austraopithecus or other living great apes OR Braincase volume increases with body mass in all three groups but it increases much faster in Homo 17 gtU39n mm 31mm TIOU39T UJID d Homology 18 Once they are physically independent ofthe parent plant developing embryos have to make their own food This is difficult when individuals are small and competing with much larger individuals Because pores cannot close water is lost at all times even when the individual is under severe water stress 19 next page E E E Raial sym etry 3 L J E a o i E g 713 Outgroup o u 0 Lu Lu Lu u v quots Jellyfish et al Comb jellies Epithelium Acoels Ectoendoderll Flatworms Annelids Protosto e develop Mollusks Roundworms Coelo Arthropods Radial symmetry Echinoderms Chordates Notochord Several possibilities nb Sponges2 should be next to existing Sponges Acoels 20 Even simple rods would be enough structure to stiffen the area around the mouth and make some biting movement possible which would make feeding more efficient Phylogenetic Trees Name Name 28 October 2011 Name The table below summarizes key traits found in some major groups of animals that have vertebrae or backbones A 1 indicates that the trait is present a 0 indicates that it is absent Assume that each ofthe traits is homologous in the groups listed for example that the limbs of lizards and mammals are derived from limbs found in a common ancestor Amniotic lactation Scales with E c L a is E Note that some snakes have vestigial hindlimbs as embryos or as adults Use these data to estimate the phylogeny of the groups Here s one way of getting started x Note that only lizards and snakes have scales with keratin meaning that they should be found next to each other on the tree joined by a common ancestor that had scales with keratin In the space to the right start your tree by connecting lizards and snakes with a ushaped bracket Add a scales label to the leftmost branch to indicate where the trait evolved Sharks and rays Scales Limbs lost wlkeratin Lizards Snakes N Now look at the Amniotic egg column Note that only lizards mammals and snakes have this trait the other groups do not Thus the amniotic egg is a synapomorphy that defines the lizards snakes and mammals as a monophyletic group Use this information to add mammals to your tree Add an amniotic egg label to show where the trait evolved Mammals Fur lactation Amphibians Internal Rayfinned fish bone 0 Examine the table again and find synapomorphies that will allow you to add rayfinned fish an amphibians to your tree Label where each synapomorphy evolved Je When you have placed all 5 groups add a 6 h branch called Sharks and rays as an outgroup 01 Which group is most closely related to the amphibians lizards or sharks and rays This is the same as asking which of the two groups shares a more recent common ancestor with amphibians Explain your reasoning Lizards because they share a common ancestor with amphibians at the node marked with a fat arrow Amphibians and sharks and rays share a common ancestor at the node marked with a skinny arrow 6 Which group is most closely related to the sharks and rays Lizards or rayfinned fish This is the same as asking which of the two groups shares a more recent common ancestor with sharks and rays Explain your reasoning They are equally closely related to sharks and rays because they both share a common ancestor with sharks and rays at the node marked with a skinny arrow 7 According to your tree are mammals higher than amphibians Explain why or why not No they are not more evolved or more advanced or more of anything else that could be construed as higher They simply have some derived traits synapomorphies that amphibians do not Likewise amphibians have derived traits that mammals do not Amphibians and mammals are both tips on the tree not steps on a ladder Biologically higher is meaningless 8 Snakes don t have limbs Do they really belong in a monophyletic group with vertebrates that do have limbs Explain why or why not If appropriate add a limbs lost label to your tree Yes there is strong evidence including the presence of vestigial traits supporting the hypothesis that their ancestors had limbs During the evolution of snakes limbs were lost 9 Relative to the common ancestor of all the bony vertebrates meaning the common ancestor of all ofthe groups on the tree except for sharks and rays which ofthe groups on your tree has been evolving for the longest amount of time Explain your reasoning All of the species living today have been evolving for the same length of time since their common ancestor existed 10 Sharks and rays don t have bony skeletons they have cartilaginous skeletons ls either of the following statements correct Explain why or why not a Sharks and rays are a basal you could also say primitive or ancestral group relative to the vertebrates b Cartilaginous skeletons are a basal you could also say primitive or ancestral trait relative to the bony skeletons of vertebrates Statement b is correct a is not The sharks and rays living today are descended from ancestors with cartilaginous skeletons that lived long ago But those ancestors were not the same as today s sharks and rays So sharks and rays may have some primitivebasallancestral traits meaning traits retained from that ancestor but the shark and ray species living today are not primitive or basal or ancestral This is true of all species Humans retain ancestral traits such as the vestige of a tail genes comprised of DNA presence of limbs and so on Please turn the completed exercise in to your TA and make sure that your names are legible We ll send you an answer sheet to the exercise on Monday via email Biology 180 Week 3 Study Questions Autumn 2011 Do these questions with your study group N4 people Follow these rules 0 Everyone must participate in every question that you work on 0 Listen to each person s contributions 0 At least once during each study session each group member should challenge another member s ideas 0 Assign roles If your group isn t part of a large session at CLUE or Tribeta or the IC one person should serve as timekeeper one as organizer keeping people on task and getting a consensus on when to move on to the next question for discussion one as groupdynamics checker making sure everyone is heard and respectful one as challenger making sure that all ideas are carefully considered 0 4a God is changing the characteristics of weeds 0 4b When weeds strive to grow in the presence of herbicides their characteristics change in ways that make them better able to grow in this environment They pass these traits on to offspring so the population changes over time 0 4c Weed populations have heritable variation for herbicide resistance Individuals with alleles for resistance produce more offspring than individuals without those alleles As a result the frequency of resistance alleles increases over time Format 1 Each person should write answers to the rst 5 questions on their own in 25 minutes or less these questions would be worth about 50 points on an exam 2 Discuss each question 3 minutes each 3 Exchange papers and use the answer key on p3 to grade each other for full credit partial credit or no credit 1 minute each 4 Read through the rest of the question list Each person should decide which question they want to work on most meaning that they are LEAST confident about 5 Go through the rest of the questions taking turns to decide which to discuss next 6 Each member of the group should write 2 exam questions based on key concepts from this week identi ed in your weekly notes summary Use these questions to quiz each other 1 Consider the principle of segregation and the principle of independent assortment An individual s genotype is Rr Draw and label An individual s genotype is EeRr Draw and label chromosomes from this individual that illustrate chromosomes from this individual that illustrate why why the principle of segregation occurs the principle of independent assortment occurs What phase of mitosis or meiosis specify which What phase of mitosis or meiosis specify which does this occur in does this occur in l 2 The drawings in this question are all from the same individual c What is haploid number in this species Q d What is the ploidy of the cell in part b II A The cell s genotype is AABBDdEe b The cell s genotype is QRtqRT reiativeto each other you don t Place the alleles on the chromosomes Place the alleles on the chromosomes need to know which genes are Is this mitosis meiosis I Is this mitosis meiosis I actually on which specific or meiosis II or meiosis ll chromosomes E e Put quotPSquot at the top of the drawings that illustrates the principle of segregation Explain why 390 f Put PIA at the top of the drawings that illustrates the principle of independent assortment Explain why 3 Identify whether the following situations are examples of sexlinkage linkage recombination multiple allelism co dominance incomplete dominance polygenic inheritance pleiotropy gene x gene interaction or gene x environment interaction Mendel worked with only two alleles of each trait that he examined But researchers have identified over 500 alleles at the gene involved in the human disease cystic fibrosis Hemoglobin is the oxygencarrying pigment in blood If you carry the 8 allele and the N allele you will have both the S and N types of hemoglobin in your blood cells Obesity and type 2 diabetes are rare in Pima Indians who live a traditional lifestyle in Mexico But obesity and type 2 diabetes are extremely common in Pima Indians who live a modern lifestyle in the United States 4 Suppose that in Daphnia magna genes L and B are linked but are more than 50cM apart meaning that crossing over occurs between them 50 ofthe time on average A dominant allele L contributes to long antennae while a recessive allele contributes to short antennae A dominant allele B contributes to large body size while a recessive allele b contributes to small body size An LBlb male mates with an LBlb female and produces offspring Phenotypes of parents Gametes genotypes produced by parents F1 Punnett square Phenotypes observed in F1 progeny and their ratios Using these data as an example explain how crossing over contributes to phenotypic variation in populations 5 Suppose that in peas the Yand R genes are so tightly linked that crossing over almost never occurs between them Now suppose that Mendel only worked with seed color Y and seed shape R not the other 5 traits Would he have discovered the principle of segregation and the principle of independent assortment Explain your answer Answers to Questions 15 R Eliloi 0 ll i 2 ill ll Anaphase of meiosis Metaphase of meiosis 1 ITI 70 II IIquot 2 The drawings in this question are all from the same individual c What is haploid number in this species d What is the ploidy of the cell in part b diploid a Mitosis b meiosis E e e Alleles on homologous chromosomes are pulling apart and will end up in different gametes f Paternal and maternal chromosomes can line up in any order in metaphase of meiosis I so every possible combination of chromosomes and alleles is possible in daughter cells 3 Multiple allelism Codominance Gene x environment interaction 4 Phenotypes of parents both have long antennae and large body size Gametes genotypes produced by parents both produce Lb LB 13 and lb in equal proportions Phenotypes observed in F1 progeny and their ratios 9 long antennae large body size 3 long antennae small body size 3 short antennae large body size 1 short antennae small body size Because crossing over occurred new phenotypes appear in the F1 generation Speci cally crossing over generates individuals with long antennaesmall body size and short antennaelarge body sizeithese would not have appeared without crossing over 5 He would ve discovered the principle of segregation but not the principle of independent assortment In each monohybrid cross he would ve observed a 31 dominant1recessive phenotype ratio in the Fzs consistent with the principle of segregation But he also would ve observed a 31 dominant1recessive phenotype ratio in the Fzs not consistent with the principle of independent assortment Additional questions 6 Consider the following data on Inuit residents of Barrow Alaska When these data were collected people over 35 had not attended Americanstyle schools that required extensive reading but people under 35 had Myopia is near sightedness Age diagnosed myopic sample size 635 42 348 3688 5 160 State whether these data are evidence of a gene X gene or a gene X environment interaction Explain your logic 7 Consider the following X linked genes in fruit flies ebony normal body color X9 black body color white XW normal eye color red X white eyes yellow Xy normal body color X yellow body color Write the genotype of a female that has one X chromosome with all three dominant alleles and one X chromosome with all three recessive alleles What is her phenotype List the gametes produced by this female if no crossing over occurs Write the genotype of a male that has white eyes and normal body color List the gametes produced by this male 8 A female fruit fly with ruby eyes forked bristles and ebony body mates with a male with normal eyes normal bristles and normal body color he is homozygous XR normal eyes XF normal bristles E normal body color Xr ruby eyes Xf forked bristles e ebony body Write the parental genotypes Draw the parental genotypes draw and label the chromosomes F1 Punnett square What are the F1 phenotypes and frequencies or ratios Females all normal eyes bristles and body color Males all ruby eyes forked bristles normal body color Assume no crossing over occurs How many different gamete genotypes will the F1 females produce Assume no crossing over occurs How many different gamete genotypes will the F1 males produce 9 ln Bio 180 recently the average grade for students who reported that they took AP or lB Biology was 27 with a standard error of 009 The average grade for students who reported that they had not taken AP or lB Biology was 26 with a standard error of 006 A statistical test returns a p value of 030 Graph the data using the axes to the right Label the axes 30 The p value represents a probability Of what The probability of observing the results by chance Avg grade 25 that the null is correct Bio 180 What statistical analysis was appropriate here a t test or a linear regression t test What can you conclude from the analysis With APlB No APlB On average there is no difference in Biology 180 grade based on whether students took AP or lB biology in high school 10 A pea plant has the genotype PTpt Ee List the gamete genotypes produced by this individual assuming that no crossing over occurs With each genotype make a drawing that shows what the parent s chromosomes looked like during meiosis just before the chromosomes separated into the daughter cells that later became gametes Gamete genotypes Drawings here Make sure your upper to the right and lowercase letters are distinct below 11 Consider the following alleles in humans SHOW YOUR WORK XH black hair XE roundish eyes Ttaller D darker skin color X blonde hair Xe almondshaped eyes tnot as tall d lighter skin color NOTE the Tand D genes are linked A Chinese man with black hair and almond eyes is homozygous for not as tall and darker skin color He marries a Finnish woman who is homozygous for blonde hair roundish eyes taller and lighter skin color Genotypes of these parents Gamete genotypes Punnett square Genotypes and frequencies of F1 offspring Phenotypes and frequencies of F1 offspring Gamete genotypes produced by F1 FEMALE offspring when no crossing over occurs between the genes in question Gamete genotypes produced by the F1 FEMALE offspring when crossing over occurs between the hair and eye color genes and between the heightand skin color genes 12 Below draw the replicated chromosomes of a haploid cell in a species where n 6 Consider the cell below What is its Haploid number Ploidy Is it undergoing mitosis or meiosis Jg quot 13 Why did the results of Mendel s monohybrid cross conflict with the predictions of Blending inheritance Inheritance of acquired characters Consider Dr Bradshaw s experimental cross between M lewisii and M cardinals In the top graph plot the distribution of flower color phenotypes in the F2 offspring In the next graph plot the distribution you d expect to see in the F3 offspring after the Fzs were exposed to bees which prefer purple flowers and hummingbirds which prefer red flowers in the field Suppose the experiment had been allowed to run another 100 years In the bottom graph plot the distribution you d expect to see at the end of the experiment 30 of individuals 0 30 of individuals 0 3O of individuals purple 4 Flower color red 15 The cell to the right is from a diploid organism with n 5 Draw what the chromosome look like in anaphase of meiosis You can use dashed or dotted or colored lines as well as Distinct sizes and shapes to indicate different types of chromosomes 16 The cell to the right is from a diploid organism with n 5 Draw what the chromosome look like in metaphase of meiosis ll You can use dashed or dotted or colored lines as well as Distinct sizes and shapes to indicate different types of chromosomes 17 A fruit fly with the genotype xmxm RHRH mates with an XWTY rhrh individual Draw the unreplicated chromosomes present in the parents and label the alleles Gamete genotypes write these don t draw Punnett square F1 genotypes and proportions In the space to the right write the genotypes of all possible gametes produced by F1 females if crossing over occurs between the Wand T genes on the X chromosome but no crossing over occurs between the R and H genes 18 Consider the following garden pea cell What is the haploid number What is the ploidy lsthis meiosis l meiosis II or mitosis Which phase This individual s genotype is PpTTYyRRHH DEde SBSB Label the alleles on the chromosomes In answering you may use just one some or all ofthe chromosomes provided 19 Instead of being XY or XX humans with Turner s syndrome are XO meaning that they have a single X chromosome This is thought to occur when a sperm cell lacks a sex chromosome because of a defect in meiosis Make a drawing showing a homologous pair of autosomes nonsex chromosomes separating normally and the X and Y separating in a way that could lead to Turner s syndrome Label the X and Y Is this meiosis l or meiosis ll What phase of meiosis should be illustrated Answers to additional questions 6 Gene X environment interaction The genetic makeup of the population did not change but the environment did Now people who had a genetic predisposition to myopia are now expressing the trait 7 XEWYXewy Normal body color and normal eye color Halfyare XEWY half are XeWy W Half are XEWY half are Y 8 x xquot ee XRFY EE r r R Y e e I E E f f F F1 Punnett square X fe Females all normal eyes bristles and body color Males all ruby eyes forked bristles normal body color 4 4 9 30 The probability of observing the results by chance Avg grade that the null is correct Bio 180 t test 25 On average there is no difference in Biology 180 grade based on whether students took AP or IE biology in high school With APIB No APIB 10 Gamete genotypes Drawings here Make sure your upper to the right P p P p and lowercase letters are distinct below P TE P Te LtE gte 11 Genotypes ofthese parents X 9 Y tDfD and XquotEXquotE TdTd Gamete genotypes 12 X 9 tD AYQ all X E Punnett square xquotE Td x 9 Q XHSXquotE tDTd Y Q XquotEY tDTd Genotypes and frequencies of F1 offspring males all XquotEY tDTd fem ales xHex E tDTd Phenotypes and frequencies of F1 offspring m s all blonde hair roundish eyes more height darker skin Females all black hair roundish eyes more height darker skin Gamete genotypes produced by F1 FEMALE offspring when no crossing over occurs between the genes in question x 9 Q X 9 E X Q WEE E offspring when crossIng over occurs between the XHE E XHEt Xquot9 E Xquot9 tg hair and eye color genes and between the height and skin color genes 12 Below draw the replicated chromosomes Consider the cell below What is its ofa haploid cell in a species where n 6 Haploid number 4 Ploidy Diploid Is it undergoing mitosis or meiosis 39 Meiosis K 13 White and purple alleles for example did not blend the phenotype associated with thewhite allele showed up intact in the F s White for example showed up in the Fzs but was not acquired in the Fls 14 m 1 Cunsmm w wadsmwsuxwimmmal Lu W deecv M WWW M Glam mme mine warm w immummm quotmm min mum in Mam n 30 x90 m ample w llawxsl m it an WW 0 s Elrrex we w um new means mm mammmyeavs mite mmmg rn an v mam msmuman nuuuwunm ii In in m rte Exrxmmnl A at miwmt Mimi gt ma Fluwnr aim 15 and 16 A g 9 15 t y a f9 i ll 17 Female Male Draw the unreplicated case letters are distinct H Gamete genotypes Female all X M Male 12 XWT rh 12Y rh write these don t draw Punnett square XWT rh Y m x M XW XW RHrh F1 genotypes and proportions Females all X quot XWT RHrh males all XW39Y RHrh In the space to the right write the Xw39 genotypes of all possible gametes Xw39 rh produced by F1 females if crossing X M over occurs between the Wand T X m genes on the X chrom osom e but no crossing over occurs between the R and H genes 18 lamp What is the haploid number 7 H o What is the ploidy Diploid 2 2n R H R d lsthis meiosis l meiosis II or mitosis 739 E Meiosis l 7 Which phase prophase Y S y This individual s genotype is PpTTYyRRHH DElde SBISB S B Label the alleles on the chromosomes just the positions relative to each other need to be correct 19 Instead of being XY or XX humans with Turner s syndrome are XO meaning that they have a single X chromosome This is thought to occur when a sperm cell lacks a sex chromosome because of a defect in meiosis Make a drawing showing a homologous pair of autosomes nonsex chromosomes separating normally and the X and Y separating in a way that could lead to Turner s syndrome Label the and Y Is this meiosis l or meiosis ll MBIOSISl What phase of meiosis should be illustrated ana phase Biology 180 Week 6 Study Questions Autumn 2010 Does these questions with your study group 4 people Follow these rules Everyone must participate in every question that you work on Listen to each person 5 contributions At least once during each study session each group member should respectfully challenge another member s ideas Assign roles If your group isn t part of a large session at CLUE or Tribeta or the IC one person should serve as timekeeper39 one as organizer keeping people on task and getting a consensus on when to move on to the next question for discussion one as groupdynamics checker making sure everyone is heard one as challenger making sure that all ideas are carefully considered Format 1 Each person should write answers to the first 5 questions on their own in 20 minutes or less these questions would be worth about 40 points on an exam 2 Discuss each question 3 minutes each 3 Exchange papers and use the answer key on p3 to grade each other for full credit partial credit or no credit 1 minute each 4 Each member of the group should write 2 exam questions based on key concepts from this week identified in your weekly notes summary Use these questions to quiz each other 1 SINES are genes that can be inserted into chromosomes SlNEs118 have been analyzed in the artiodactyls SINE 1 2 3 4 5 6 7 s 9 1o 11 12 13 14 15 16 17 1s ow o o o o o o 1 1 1 1 1 1 1 1 1 1 o 0 Deer o o o o o o 1 1 1 1 1 1 1 1 1 1 o 0 Whale 1 1 1 1 1 1 o 1 o 1 1 o o o o 1 o o Hippo o o 1 1 1 1 o 1 o 1 1 o o o o 1 o o Pig 0 o o o o o o o o o 1 o o o o 1 1 1 Peccaw o o o o o o o o o o 1 o o o o 1 1 1 Camel o o o o o o o o o o o o o o o o o o Add pig and peccary to the tree Map the origin of the Camel SINEs that identify them as a monophyletic group Suppose the closest living relative to artiodactyls was Hippo added as an outgroup What SINEs would be found in this lineage according to the data above Whale Map the origin of SINEs that identify whales as a monophyletic group C Deer Cow Are hippos more closely related to cows or pigs Explain your reasoning 2 Define what a species is and explain why it is logical to identify them on the basis of morphological differences Definition of a species Why morphospecies criterion is logical One strength of morphological species concept One weakness of morphological species concept 3 Squid are molluscs Humans are vertebrates a Both have imageforming camera eyes Is this type of eye homologous in these species or is it an example of homoplasy Explain your answer b Both have a muscular heart that is involved in circulating body fluids Is the presence of a heart homologous in these species or is it an example of homoplasy Explain your answer 4 Two populations of apple maggot fly have been identified One lays eggs in hawthorn fruit the other lays eggs in apple fruit Fly larvae eat the fruit Hawthorn and apple trees often grow side by side Individuals from the two populations look identical but have distinctive genetic characteristics Only about 5 of all matings occur between members of the two populations 95 of matings occur within each population because most matings take place on fruit a How would you test whether these two populations should be considered separate species under the following species concepts Biological Phylogenetic Morphospecies b If speciation is occurring what is causing the two populations to become genetically isolated c If speciation is occurring generate a hypothesis for which evolutionary force or forces is causing the populations to diverge genetically 5 In many areas of the world habitats are being fragmented into tiny patches as cities and agricultural areas expand Does this process qualify as a vicariance event If so what affect might it have on the populations that occupy the isolated patches Answers to questions 15 1 Add pig and peccary to the tree Map the origin of the Camel SlNEs that identify them as a monophyletic group Peccary Pig 1718 Suppose the closest living relative to artiodactyls was Hippo added as an outgroup What SlNEs would be found in this lineage according to the data above Whale 1 None all of these SINEs were inserted after artiodactyls evolved Map the origin of SlNEs that identify whales as a monophyletic group I Deer Are hippos more closely related to cows or pigs Explain your reasoning Cow Cows because they share a more recent common ancestor with cows than they do with pigs A population or group of populations that is evolving independently of other populations If a population is evolving independently then it should have unique morphological characteristics traits that aren t observed in other populations acquired via mutation selection and drift widely applicable OR works for fossil species OR works for asexual species OR strong theoreticalconceptual foundation experts can disagree about whether differences between forms are consistent with normal withinspecies variation or represent synapomorphies traits that arose independently 3 a Because squid and humans are not closely related and because other mollusks and vertebrates do not imageforming camera eyes the similarity is due to homoplasy They result from convergent evolution based on natural selection favoring the ability to see focused images b Other mollusks and vertebrates have hearts as do most species of animals that are closely related to mollusks and vertebrates Thus the traits are homologous The trait is shared because it existed in a common ancestor 4 a Need to determine if 5 hybrid matings are enough to homogenize gene frequencies in the two populations Apparently not if the two populations are genetically distinct Need to estimate the phylogeny ofthese populations to determine if they each have enough unique shared derived characters to make them come out as independent tips Need to study morphological traits to see if there are any distinguishing features need to include traits like chemical attractants courtship displays etc b Lack of gene flow because individuals select different fruits and mate there 8V Natural selection might favor alleles that allow offspring to thrive on apple fruit better than hawthorn fruit and vice versa 5 Fragmentation of habitats is called vicariance lf populations inside patches are isolated in terms of gene flow they should begin to diverge due to genetic drift and natural selection Additional questions 6 Considerthe following phylogeny of the mammal group called artiodactyls Carnivores a Identify and label Camel the root of the tree 3 monophyletic groups Peccary the outgroup the common ancestor of whales and hippos Pig the common ancestor of all artiodactyls Whale Deer Cow b Name a shared derived trait that helps identify the whales dolphins and porpoises as a monophyletic group What logic did you use to support the hypothesis that this character is derived from a common ancestor c Are the limbless streamlined bodies of whales and dolphins homologous or due to homoplasy Explain your reasoning 7 Considerthe small group of iguanas that rafted onto an island in the Caribbean where no iguanas existed previously Suppose that the new population remained genetically isolated from other iguana populations in the Caribbean Would you expectthat the new population will eventually form a new species Why orwhy not 8 The phylogenetic tree below shows the evolutionary relationships among eight species Three of these are nocturnal they are active at night and five are diurnal active during the day ABCDEFGH Diurnal Nocturnal a Species A and F are both nocturnal ls nocturnal activity in these two species homologous or due to homoplasy Explain b Species F and G are also both nocturnal ls nocturnal activity in these two species homologous or due to homoplasy Explain 9 Why do phylogenies have to be estimated via an analysis of homologous traits Why might DNA sequences qualify as a homologous traits How can a researcher determine if a morphological trait is homologous 10 The evolution ofthe limb in the lineage that became known as tetrapods was one ofthe great events in the history of life Why Describe the fossil evidence that limbs evolved from the fins of lobefinned fish 11 The landmass called Central America arose about 3 mya Prior to this event the Atlantic and Pacific Oceans were continuous in the region and there were several species of snapping shrimp present Three ofthese species AP1 AP2 and AP are shown on the phylogeny to the right Once Central America had separated the Atlantic and Pacific distinct A1 species evolved on either side Species called A1 and P1 evolved from AP1 P1 species A2 and P2 evolved from AP2 and species A3 and P3 evolved from AP3 In the space to the right draw the phylogeny of the 6 derived species On your tree label the node that represents species AP2 AP Was this an example of vicariance dispersal or sympatric speciation Explain why A1 and P1 have diverged in terms oftheir genetic and morphological characteristics 12 Consider speciation What does it mean to say that different species are evolving independently 0 Why is the morphospecies concept a good criterion for deciding that species are evolving independently 0 What is a drawback of the morphospecies concept 0 Why is the phylogenetic species concept a good criterion for deciding that species are evolving independently 0 What is another advantage of the phylogenetic species concept 13 Consider data on the evolution of whales Indohyus lndohyus A m bulocetus Delphinapterus Rhodocetus Whale ear Dorudon Dorudon one Rhodocetus Fully aquatic life Delphinapterus A mbulocetus a b d e h Are the two trees the same or different According to the tree on the right which species is most closely related to Indohyus Ambulocetus or Delphinapterus quot39quot 39 39 39 is n unusual ear bone All ofthe species on the trees have this bone On the tree to the right mark and label the origin of quotWhale ear bone Hippos do not have this unusual ear bone On the tree to the right add hippos Indohyus Ambulocetus and Rhodocetus were semiaquatic spent time on land water According to the tree on the le is the group called semiaquatic whalesquot monophyletic or paraphyletic Dorudon and Delphinapterus are fully aquatic spend no time on land On the tree to the le mark and label the origin offully aquatic life con ict with quot uny mm Dom t a laon evolved from terrestrial species Explain your logic Delphinapterus is the beluga whale living today Indohyus Indohyus is dated a 50 mya Ambulocetus at 48 m aRh at 47 mya Dothese data on time support or con ict with the hypothesis that whales evolved from terrestrial and semiaquatic species that had hindlimbs Explain your logic Structural analyses ofthe tiny Dorudon bones indicated by the arrow suggest that they 1 are homologous with the hips and leg bones found in other mammals but 2 w re not functional Do these data support or con ict with the hypothesis that whales evolved from terrestrial species Explain your logic Dorudon o 5llli tfm mf V I mm 39 M f m Delphinapterus 14 Considerthe phylogenetic tree of species 17 Draw an arrow to the common ancestor of 17 Which species 17 is most closely related to 2 this common ancestor 3 4 Which species shares the most traits With this common ancestor 5 6 Circle a monophyletic group 7 Which species is the closest outgroup to the monophyletic group you identified Pat Lulrving Go Dawgs is working on the phylogeny of plants in the verbena family which have a variety of fruit types Her tree indicates that fleshy cherrylike fruits evolved several times independently lfthis were the case in species 17 name two species that might have fleshy fruits and five that would not have fleshy fruits Yes fleshy fruits No fleshy fruits If she looks into the genetic and developmental mechanisms responsible for the fleshy fruit trait predict what she will find when she compares the species that evolved fleshy fruits independently Explain your answer 15 The evolution of vasculartissue was a key event in the history of land plants because it provided a support structure and an efficient system for transporting water and nutrients Biologists have found fossils that have an array of vascular cell types ranging from extremely simple to more complex structures that are virtually identical to those found in plants today If the hypothesis that today s vascular tissue evolved from simpler cells is correct what should the following independent sources of data show Relative dating Radiometric absolute dating Phylogenies estimated from traits other than vascular tissue you can write or draw your answer your choice 16 Aphids are insects that make a living by sucking plant sap Sarah Via has found that the aphids that feed on clover are genetically distinct from the aphids that feed on peas She claims that the pea aphids and clover aphids are in the process of becoming different species How is it possible given that pea and clover fields are often adjacent to each other meaning that gene flow could be extensive 17 Fill in the following chart using examples of adaptive radiations discussed in class or in the text Lineage Trigger Identify the opportunity Why would this opportunity or innovation lead species cause or innovation 0 rapid speciation and extensive involved 39 39 39 39 quot g Ecological opportunity Morphological innovation Answers to additional questions 6 Outgroup Carnivores many monophyletic groups are possible Camel including each tip Peccary Root Pig Hippo common ancestor of all artiodactyls 7 Whale common ancestor of whales and hippo Many traits possible aquatic habitat streamlined bodies lack of hind limbs paddlelike forelimbs etc Other close relatives eg other artiodactyls lackthese features and all are shared by whales dolphins and porpoises Homologous they are similar because they were present in the common ancestor of these two groups 7 Yes genetic drift will cause them to be genetically distinct from the source population and ifthe habitat on the new island is unlike that on the source island then natural selection should cause further divergence 8a It is due to homoplasy The common ancestor of species A B and C was probably diurnal The common ancestor of species DEFG and H was also probably diurnal Thus nocturnal behavior evolved independently in the lineages leading to species A and F b It is homologous The common ancestor of F and G was probably nocturnal so the two species share the derived trait 9 Otherwise species might be grouped on the basis of traits that appear similar but are not derived from a common ancestor Because genes are transmitted from parents to offspring DNA sequences from related individuals and populations are derived from a common ancestor Homology has to be inferred on the basis ofthe trait s presence in closely related species 10 It is considered a great event because the limb allowed tetrapods to move about efficiently on land Fossil evidence phylogenies estimated on the basis of morphological traits observed in fossils other than the limb show that lobefinned fish and tetrapods are closely related they are sister groups that are next to each other on the phylogeny The dates of early lobefinned fish and early tetrapods and sequence of branches in the phylogeny of these groups describe a sequence of changes that elongated homologous bones into a functioning limb in terrestrial groups 11 A1 Pl A2 P2 A3 P3 Vicariance Because there is no gene flow across the Central American landmass the populations on either side began evolving independently Mutation drift and selection on either side would lead to rapid divergence 12 Because there is no gene flow an allele frequency change in one species has no impact on allele frequencies in the other population Genetic isolation and divergence should produce identifiable morphological differences Experts can disagree about how much divergence represents normal variation within species and how much divergence indicates that speciation has occurred It does not address important divergence in songs displays biochemistry or other nonmorphological traits Genetic isolation and divergence should produce synapomorphies that identify species as monophyletic groups distinctive tips on a tree of populations It is widely applicable can be used with any species living or fossil ll AP Hippos Indohyus Indohyus Ambuocetus Delphinapterus Rhodocetus Whale ear Dorudon Dorudon bone Rhodocetus Fullyaqua clife Delphinapterus n r aSame b equally closely related c see tree d see tree e paraphyletic f see tree g Support At every node the descendantderived species have shorter hindlimbs and are more whalelike fully aquatic than the ancestral group Or Support The ancestral state at the common ancestor with hippos is semiaquatic living or terrestrial ifthe outgroup is pigs mapping fully aquatic life shows that it is clearly derived Note that the sister groups to hippos and pigs are fully terrestrial h Support the semiaquatic species on the tree predate the fully aquatic species i Support The presence of vestigial limbs in Dorudon is consistent with the hypothesis that hindlimbs used for walking existed in the terrestrial ancestors of whales but were lost during the evolution of fully aquatic life due to selection for ability to swim versus walk 14 arrow to base leftmost node all equal cannot tell from information given many possibilities for next 4 questions The mechanisms will be different NOT homologous because homologous structures can only be produced by homologous genes and developmental mechanisms 15 The simpler types of cells should be found in older rocks than the more complex cell types OR The simple vascular cell types should appear first in the fossil record The simpler types of cells should be found in older rocks than the more complex cell types OR The simple vascular cell types should appear first in the fossil record The phylogenies should show that the ancestor of all vascular plants had the simplest types of vascular cells known and that each divergence produced descendants with more complex types of vascular cells Outgroup no vascular cells Simplest vascular cells Slightly more complex vascular cells Complex vascular cells Vascular cells like those found today 16 If pea aphids only mate on peas and clover aphids only mate on clover then gene flow would be drastically reduced or eliminated Because pea and clover represent different environments there would be strong selection for divergence based on alleles that increase fitness on pea versus clover 17 Fill in the following chart using examples of adaptive radiations discussed in class or in the text Lineage Trigger Identify the opportunity or Why would this opportunity or innovation lead to species cause innovation rapid speciation and extensive morphological involved divergence Must identify colonization Must linkthe availability of new resources to Many possible or other mechanism that mechanisms of speciation isolationdivergence Ecological leads to lack of 1pt and morphological divergence selection opportunity competition abundant 1pt eg strong selection for traits that allow resources available efficient use of new resources Must identify the Must identify how the new trait enables individuals appropriate new trait to acquire newabundant types of resources and Many possible Morphological linkthis to selection for divergence in resources 1pt innovation usedmorphological traits Biology 180 Week 8 Study Questions Autumn 2011 Does these questions with your study group 4 people Follow these rules Everyone must participate in every question that you work on Listen to each person 5 contributions At least once during each study session each group member should respectfully challenge another member s ideas Assign roles If your group isn t part of a large session at CLUE or Tribeta or the IC one person should serve as timekeeper39 one as organizer keeping people on task and getting a consensus on when to move on to the next question for discussion one as groupdynamics checker making sure everyone is heard one as challenger making sure that all ideas are carefully considered Format 1 Each person should write answers to the first 4 questions on their own in 15 minutes or less these questions would be worth about 35 points on an exam Discuss each question 3 minutes each Exchange papers and use the answer key on p3 to grade each other for full credit partial credit or no credit 1 minute each Each member of the group should write 2 exam questions based on key concepts from this week identified in your weekly notes summary Use these questions to quiz each other bWN 1 Consider sexual selection Define the fundamental asymmetry of sex In many species of fungi sexual reproduction occurs but gametes are never produced cells that are part of the normal body of different individuals merge and their nuclei fuse to form a zygote Can sexual selection occur in these species Explain your reasoning 2 Consider consumption a Alder a tree species with nitrogenfixing bacteria has a carbontonitrogen CN ratio of 191 Willow and poplar which do not have Nfixing bacteria have CN ratios of 261 and 421 respectively If caterpillars are given a choice of eating alder willow or poplar predict the order of species they prefer Explain why bRecal the mussels in Maine preyed on by crabs Suppose mussels from highpredation HP and lowpredation LP areas of the same bay are swapped via transplantation at quotStart Make bar graphs showing the predicted results if average shell thickness relative to overall body size is measured 2 years later quotEndquot on the transplanted individuals Start HP EndLP Start LP EndHP c Predict what the offspring quotOquot of the quotEndLPquot parents will look like in terms of relative shell thickness if they end up growing in the array of habitats indicated here NP no predation rent 0 in HP 0 in LP 0 in NP quotEndLPquot 3 Adenoviruses cause colds You want to test the hypotheses that 1 adenoviruses induce sneezing in humans to increase their chance of being transmitted to uninfected people 2 infected hosts sneeze to rid themselves of adenoviruses and 3 sneezing has nothing to do with viral infection You have a drug that inhibits sneezing so you can compare large random samples of sneezers versus nonsneezers What you will measure Prediction of hypothesis 1 Prediction of hypothesis 2 Prediction of hypothesis 3 4 Consider sexual selection again 0 Why is sexual selection expected to be most intense in males 0 If it is what are the consequences 0 In red deer what data suggest that sexual selection actually is more intense in males than in females Answers to questions 14 1 o In most species females invest much more in offspring than males do No There is no difference in the investment that the two members of the mated pair make in offspring so there is no difference in what limits their reproductive success and no difference in access to mates 2a They should eat alder first then willow then poplar lfthe nitrogenlimitation or nutrientlimitation hypothesis is correct then the caterpillars should benefit from eating species with the highest ratio of nitrogen available Forfull credit state correct order and articulate that logic relate demand for N as a limiting nutrient to variation in availability 2bc Average shell thickness relative to overall body size H H Start HP EndLP Start LP EndHP Average shell thickness relative to overall body size Parent 0 in HP 0 in LP 0 in NP l EndLP39l 3 Measure duration andor severity of cold symptoms and number of uninfected people infected after contact with individuals in the study Prediction of hypothesis 1 Sneezers will infect many more people than nonsneezers Prediction of hypothesis 2 Sneezers will have more shorter andor less severe colds than nonsneezers Prediction of hypothesis 3 There is no difference in numberinfected or cold severity between sneezers and nonsneezers 4 0 In males reproductive success and thus fitness is limited by the ability to find a mate or mates As a result alleles that lead to increased success in mating are under intense selection they should spread very rapidly in the population In contrast any allele that reduces success in finding a mate should be eliminated very rapidly 0 In most species males are larger andor have elaborate morphological traits used in courtship or perform elaborate courtship displays Variation in reproductive success is much higher in males than in females Stated another way a few males are extremely successful at obtaining mates while most others do very poorly Additional questions 5 Consider altruism Why do prairie dogs give alarm calls when close relatives are near Altruism cannot evolve Explain why spiteful behavior defined as a social interaction in terms of the fitness effects on the actor and recipient cannot evolve either 6 ln birds called phalaropes females lay eggs but males build the nest do all of the incubation and spend several weeks feeding and protecting the young after hatching with little or no help from the female Predict which sex is larger and more brightly colored and explain why 7 Define the following terms Competitive exclusion principle Niche Resource partitioning Interspecific competition Character displacement 8 Explain how niche or resource partitioning could lead to 35 species of insects feeding on same plant species 9 Suppose a hurricane swept 20 individuals of two lizard species onto the same island The niches of these two species overlap extensively but not completely Predict the fate ofthe two species on this island over time Explain the logic behind your prediction 10 Design an experiment to test the hypothesis that Douglas fir and western redcedar have overlapping niches but that Douglas fir outcompetes redcedar in drier soils while redcedar outcompetes Douglas fir in wet soils Species A Species B 11 Fruit fly species A and B lay their eggs in rotting fruit lnitially their niches are measured as graphed to the right resource On the graphs below plot how their niches would used be expected to change overtime if competition is symmetric versus asymmetric with B as the slightly better competitor 0 3 5 7 0 5 14 1 Acidity of fruit pH Symmetric competition Asymmetric competition resource used 14 35 7 105 7 105 Acidity of fruit pH Acidity of fruit pH 12 Recall experiments that showed that mussels increase their attachment strength and shell thickness in response to flows of water from areas occupied by either a crab or broken mussel shells Is the change in mussel attachment strength and shell thickness an induced defense or a standing defense Explain your answer Suppose that crabs are abundant near a mussel all its life and that it develops an extraordinarily thick shell and high attachment strength as a result Would these traits be passed on to its offspring Explain why or why not You might not consider mussels to be very bright How do they know that crabs or broken mussel shells are nearby 13 Summarize the topdown Nlimitation and defense hypotheses of herbivory What question are these hypotheses trying to answer What does it mean to claim that the topdown Nlimitation and defense hypotheses of herbivory are not mutually exclusive 14 Why do some species have induced defenses while others have standing defenses Stated another way under what circumstances would natural selection favor induced defenses rather than standing defenses 15 Explain the term quotcoevolutionary arms racequot Specifically why is an arms race an appropriate metaphor for hostparasite interactions What is quotcoevolutionaryquot about the interaction 16 The text describes how snails that are infected by a certain fluke species are more likely than uninfected snails to move into brightly lit areas The flukes also occupy the snails tentacles and actively wriggle back and forth Design an experiment to test the hypothesis that snails infected by flukes are more likely to be eaten by birds than uninfected snails 17 Trypanosomes are parasites Their life cycle has a stage that occurs in tsetse flies and a stage that occurs in humans or livestock The parasite is transmitted from one host to another via bites from tsetse flies Some researchers claim that tsetse flies that are infected with trypanosomes tend to bite hosts more often than uninfected flies Design an experiment to test this claim 18 Biologists may begin using naturally occurring fungal diseases of mosquitoes as agents to control malaria Why would public health officials focus on mosquitoes to control a human disease Why might a fungus possibly be a more effective control agent than an insecticide such as DDT 19 Considerthe Nlimitation topdown and defense hypotheses to explain why the world is green Identify which hypothesis is most likely to be correct in each ofthe following situations Dry conditions have weakened trees in Alaska making them less able to make sticky sap and poisonous resins In response insects called spruce budworms have exploded in numbers and are killing the trees Caterpillars began defoliating trees in northern Minnesota one summer The infestation stopped because flies laid their eggs in the caterpillars When the fly larvae hatched they ate the caterpillars from the inside out Aphids make their living sucking sugary sap from plants They eat almost nothing but sugars formula CH20n 20 Wolves kill coyotes Why did hawks and mice increase in Yellowstone Park after wolves were reintroduced Draw a food web that helps explain your logic 21 Consider sexual selection a In 1993 a researcher found strong patterns in the preferences of men seeking women and women seeking men personal ads Which sex male or female is more likely to seek significant financial resources lndividuals of which sex are more likely to seek much younger mates than themselves b Make a graph showing how the frequency of alleles associated with red petals a trait that helps individuals attract hummingbird pollinators would have changed through time early in the evolution of Mirnuus cardinal395 Be sure to label the axes appropriately c Make a scatterplot with 10 datapoints predicting the relationship between average sexual size dimorphism in birds and degree of paternal care care by male parents eg measured as the average number of feeding visits per hour when chicks are in the nest Each data point represents a different species Add a regression line high Average sexual size dimorphism low high Amount of paternal care 22 Fill in the chart below to begin the process of designing experiments that would test alternative hypotheses other than induced defenses that could explain variation in mussel shell thickness relative to overall size among individuals You will do these experiments in the laboratory Hypothesis f 39 groups Two conditions that you will control Large random sample of mussels from the 1 same population High food availability Large random sample of mussels from the 2 same population Low food availability Mussel shell thickness 1 varies with exposure to wavetide action 23 Considerthe experiment that Connell did on barnacles in the intertidal Recall that adult Semibaanus S are found only in the lower intertidal and adult Chtharnaus C are found only in the upper intertidal a How would you test the hypothesis that adult S cannot grow in the upper intertidal b Graph the fundamental and realized niches of C and S Label them as follows C F C s fundamental niche C R C s realized niche Habitat SF S s fundamental niche P Efe em SR S s realized niche m individuals Lower intertidal lt gt Upper intertidal 24 If you pollinate Mirnuus lewisii individuals that are growing in their natural habitat by hand the number of seeds produced by the handpollinated individuals is far higher than the number of seeds produced by individuals that are pollinated by bumblebees From these data biologists conclude that intense competition is occurring for pollinators Explain their logic 25 If a grasshopper ingests a hairworm egg the hairworm grows inside the grasshopper When the hairworm is sexually mature the grasshopper throws itself into a pond or lake Grasshoppers live on land and cannot swim Once in the water the adult hairworm leaves the grasshopper and swims away the grasshopper drowns a In hairworms predict where sexual reproduction and egglaying take place land or water b Research has shown that sexually mature hairworms release signaling molecules into the brains of grasshoppers The signaling molecules affect grasshoppers when they bind to specific proteins on nerve cells in the brain Using this information predict how natural selection will act on grasshoppers in habitats where hairworms are common Answers to additional questions 5 The relatives are likely to have copies of the allele for alarm calling so the allele increases in frequency relatives survive better and reproduce more For full credit articulate concept that relatives share alleles that are identical by descent and articulate the concept of indirect fitness that alleles present in relatives can increase in frequency as a result of the altruist s actions NOTE it is perfectly acceptable to express these concepts in terms of Hamilton s rule An allele that decreased an individual s fitness while also decreasing the fitness of other individuals with or without that allele cannot increase in frequency For full credit articulate the concept that there is no mechanism for such an allele to increase in frequency 6 Females should be larger and brighter because males are making the larger investment in offspring As a result female reproductive success should be limited by access to mates while male reproductive success is limited by access to resources meaning that females should compete for mates and sexual selection will act more strongly on them than it does on males 7 lftwo species have niches that overlap completely they cannot occupy the same place at the same time The range of resources used by a species and the range of physical conditions it tolerates The use of different resources niches by coexisting species that might otherwise compete for the same resources Competition between species lntraspecific competition refers to competition within species When traits characters in two species are similar in areas where the two species exist independently but different displaced in areas where they coexist Thought to result from natural selection to minimize competition 8 Natural selection should favor individuals that do not compete with other species for the same food resources If so then over time different species should evolve to use different food resources 9 Character displacement should occur the two species should get less alike over time so that they partition resources have separate niches and do not compete 10 Plant Doug fir and western redcedar by themselves in 9 treatment groups at the same location where rainfall is low in terms of the total range occupied by the two species The treatments are 1 High humidity add water to simulate moist conditions Plant Doug fir alone western redcedar alone doug firredcedar in same plot at random locations Same density in each 2 Intermediate add water to simulate intermediate conditions Plant Doug fir alone western redcedar alone doug firredcedar in same plot at random locations Same density in each 3 Dry no added water Plant Doug fir alone western redcedar alone doug firredcedar in same plot at random locations Same density in each lfthe hypothesis is correct doug fir and western redcedar should be able to grow and reproduce in some ofthe same sites But doug fir fitness should be higher than western redcedar in the dry treatment while western redcedar fitness should be higher in the wet treatment 11 Symmetric competition Asymmetric competition resource used 0 3 5 0 14 7 1 5 7 105 Acidity of fruit pH Acidity of fruit pH 12 Induced because individuals only increase investment in defense in response to the presence of a predator No because the phenotypic change was not the result of a change in genotype and is therefore not heritable They must sense a molecule in the waterthat is released by crabs and a molecule that is released by broken mussel shells 13 Topdown number of herbivores and thus amount of herbivory is limited by predation NIimitation number of herbivores and thus amount of herbivory is limited by intake of nitrogen Nintake is limited by small percentage available in plants versus amount required by animals Defense amount of plant material available to be ingested is limited because some is indigestible or protected by toxins Why isn t more plant material eaten Why is the world green They don t exclude one another they could all be correct 14 Induced defenses should be favored if they are very expensive to produce in terms ofthe energy and resources required andor if predation is intermittent Standing defenses should be favored if they are cheap to produce in terms ofthe investment required andor if predation is a constant threat 15 The interaction is coevolutionary because the two interacting species act as selective agents that affect each others fitness It is an arms race because an adaptation that confers an advantage to one species creates a selective advantage for an adaptation in the other species that negates this advantage 16 Start with a population of genetically identical snails lnfect half with live flukes infect the other halfwith dead flukes Follow the individuals in the field Record how many are eaten by birds 17 Start with a large population of newly hatched tsetse flies none of which are infected with trypanosomes lnfect half with live trypanosomes infect half with dead trypanosomes Expose rats or rabbits or another experimental animal to tsetse flies from both treatment groups Record how often each fly bites 18 Mosquitoes that are infected with Plasmodiurn transmit the parasite to humans when they bite them Mosquitoes quickly evolved resistance to malaria but a fungal pathogen would have the potential to evolve along with mosquitoes a coevolutionary arms race might begin that would lead to better longterm control of mosquitoes 19 Defense Topdown Nlimitation 20Coyotes were no longer eating mice and wolves do not eat mice There were more mice and thus more food for hawks which increased in response coy tes h wks Frequencyof redness mlce alleles 21Women Men gt Graphs to the right 22 Time 33 25 sexualsize dimorphism low low high Amountof paternal ca re 22 hypothesis that states foodnutritionprey availability as key mechanism explaining increase in shell thickness reasonable conditions to control physical or biotic factors other than food amount that could affect shell thickness including moisture sunlight salinity predadtion wavetide action time of data collection temperature minerals in water type of substrate population density source population agehealth of mussels food type timing of feeding comparison groups no or low wavetide action vs high wavetide action Also acceptable Wave energy reciprocal experiment reasonable conditions to control physical or biotic factors other than wavetide action that could affect shell thickness No Credit from tidal zonebelow tideline lost of variationlittle variation having a control wave gro protectionno protection because it is what we are measuring control factors that are not the same for both groups low depthhigh depth wave actiontide action putting group in the same place control condition cannot be thickness location of mussel 23 Allow S to colonize rocks in the lower intertidal then transfer the rocks S individuals to the upper intertidal Record survival SF SR C Habitat preference of individuals Lower intertidal lt gt Upper Intertidal 24 The handpollination data show that the fitness of Mirnuus individuals is limited by their access to pollen andor their ability to get their pollen to other individuals Because pollinators as a resource are in short supply and have a large impact on fitness there should be intense competition to attract more pollinators Better competitors will have higher fitness 25 water There should be intense selection favoring grasshoppers that have nervecell proteins that don t bind to the hairvvorm signaling molecules and are thus unaffected Biology 180 Week 4 Study Questions Autumn 2011 Does these questions with your study group 4 people Follow these rules Everyone must participate in every question that you work on Listen to each person s contributions At least once during each study session each group member should respectfully challenge another member s ideas Assign roles If your group isn t part of a large session at CLUE or Tribeta or the IC one person should serve as timekeeper39 one as organizer keeping people on task and getting a consensus on when to move on to the next question for discussion one as groupdynamics checker making sure everyone is heard one as challenger making sure that all ideas are carefully considered Format 1 Each person should write answers to the first 6 questions on their own in 25 minutes or less these questions would be worth about 50 points on an exam 2 Discuss each question 3 minutes each 3 Exchange papers and use the answer key on p3 to grade each other for full credit partial credit or no credit 1 minute each 4 Do the remaining questions using the same sequence 5 Each member of the group should write 2 exam questions based on key concepts from this week identified in your weekly notes summary Use these questions to quiz each other 1 Consider mutation a Explain why the following types of mutation are random A change from a G to a C when DNA is copied during chromosome replication A change in chromosome number due to an error in anaphase of meiosis b Why could a change in the base sequence in the regulatory region of a gene change the phenotype c Mutation occurs at too low a frequency to be an important factor in changing allele frequencies in one generation Why is mutation a more important evolutionary force in organisms with short generation times Even in organisms with long generation times why is mutation crucial to evolution 2 Consider alleles associated with human genetic disease a In each comparison below circle the allele that would be eliminated FASTEST In each case assume that the phenotypic disease effects are equally severe Circle both if no difference Autosomal recessive v autosomal dominant Xlinked recessive v autosomal recessive Affects children vs affects 60 yearolds Autosomal recessive Some heterozygote advantage v no heterozygote advantage b Most cases ofthalassemia are caused by autosomal recessive alleles A heterozygous woman marries an affected man On average what proportion of their children will be affected c Some cases ofthalassemia are caused by autosomal dominant alleles An affected heterozygous man marries an unaffected woman On average what proportion oftheir children will be affected d Redgreen color blindness is caused by an X linked recessive An affected man marries an unaffected woman On average what proportion oftheir children will be affected Males Females 3 Two healthy parents know from blood tests that each carries a recessive allele responsible forTaySachs disease TaySachs causes nerve cells to malfunction and results in death by age 4 lftheir first three children have the disease what is the probability that their fourth child will not What is the probability of parents like these having four diseased children lftheir first three children are male what is the probability that their fourth child will be male 4 Why would evolution eventually grind to a halt if mutation did not occur 5 Suppose you are studying a population of HIV where drug resistance has increased to high frequency Will heritable variation continue to exist Will evolutionary change continue to occur Explain 6How do each of the following processes contribute to the production of genetic variation during sexual reproduction Independent assortment Crossing over Outcrossing fertilization involving a sperm and egg from different individuals Mutation Answers to questions 16 1a ltjust happens OR any change in base sequence is equally possible OR undirected with respect to fitness Same as above except any change in chromosome number is equally possible b If the timing location or amount of expression changes then the activity ofthe gene product and the phenotype changes c In a relatively short time there can be a relatively large change in allele frequency It is the only source of new alleles 2a autosomal dominant Xlinked recessive Children no heterozygote advantage b 12 c 12 d Males 0 females 0 3 1256 12 4 Natural selection and genetic drift tend to eliminate alleles and thus reduce genetic variation in populations If they acted in isolation they would eventually eliminate all genetic variation at many loci and evolution would grind to a halt due to a lack of genetic variation This trend is countered by mutation which constantly introduces new alleles and thus genetic variation 5 Mutation will continue to occur and the degree of resistance may continue to increase over time ifthe same drug continues to be used in the same way timing and dosage Eventually selection on a particular enzyme may be counterbalanced by selection on other aspects of HIV s ability to survive and reproduce and change will stop selection will become stabilizing instead of directional 6 Produces a random assortment of maternal and paternal chromosomes in each gamete Thus virtually all gametes have different genotypes Produces new combinations of maternal and paternal alleles on each chromosome Thus all chromosomes in all gametes have different genotypes Combines alleles from different individuals Thus offspring will have different genotypes from either parent Contributes new alleles in every population in every generation Additional questions 7 Molecules called tRNAs and rRNAs are crucial to the production of proteins inside cells Do these types of RNAs violate the central dogma of molecular biology Explain your reasoning 8 Huntington s disease is fatal in humans and the disease alleles are autosomal dominant The disease phenotype usually appears in afflicted individuals when they enter their 40s Explain why natural selection has not eliminated the disease alleles which have no known selective advantage 9 Researchers have tried to cure genetic diseases that are caused by deleterious recessive alleles by introducing alleles for the unaffected phenotype into affected individuals Do the researchers have to make the patients heterozygous or homozygous for the normal allele Explain your reasoning 10 What does it mean to say that alleles for polygenic traits have additive effects 11 Define the gene Your answer should include points of certainty about genes and points of uncertainty about genes Certainty is in quotes because nothing in science is absolutely certain 12 Explain what is meant by the following claims a Mutation proposes selection disposes b Mutation is random but evolution by natural selection is nonrandom 13 People called eugenicists advocate control of human mating so that people with illnesses caused by rare deleterious recessive alleles are not allowed to have children Explain why this strategy is likely to take an extremely long time to have an impact on the frequency of deleterious recessives in the population in addition to being unethical 14 Dr Toby Bradshaw Go Dawgs is studying selection on flowertraits in M lewisiiand M cardinal395 The ancestors ofthese species were pollinated by bumblebees Within each species flower traits are variable Explain where this variation came from and whether it existed prior to any pollination by hummingbirds 15 To cure human diseases that are caused by lossoffunction genes researchers have tried inserting normal alleles of genes What parts ofthe normal allele would have to be added the coding sequences the regulatory sequences or both Explain Suppose you extracted some bone marrow cells from the patient inserted the normal allele into the cells and then put the cells back into the patient s bone marrow Would the patient now be able to produce unaffected offspring Explain 16 In terms of the underlying genetics explain why quantitative traits characteristics than can take a wide range of values typically show a normal distribution in populations 17 Consider a human gene called FOX32 People with lossoffunction alleles in FOX32 have severe impairments in speaking clearly and using grammar correctly What does this observation imply about the function ofthe FOX32 gene product Compared to chimps and all other mammals humans have a change in a coding region of FOX32 The change affects how the protein product is activated What is the evolutionary significance ofthis observation Comment on the following statement The mutation occurred in FOX32 because it was beneficial it needed to happen if humans were going to live in social groups and adapt to the grassland environments of East Africa 18 In humans the Huntington s disease allele is autosomal dominant it causes death at age 45 Predict whether it s more or less frequent than an autosomal dominant that causes death at age 3 Explain Predict whether it s more or less frequent than an autosomal recessive that causes death at age 45 Explain 19 The chromosomes from your Finnish mother taller lighter skin blonde hair round eyes wavy hair and Chinese dad shorter darker skin black hair almond eyes straight hair are undergoing meiosis I Draw an arrow to indicate where recombination occurred Round Almond eyes Wavy hair Straight hair eyes Circle genetic variation that resulted from mutation Lighter Darker Skin Black hair Reddish hair skin Using the principle of independent assortment explain why all your children won t have round eyes and black hair Taller Shorter Prior to meiosis the DNA in a chromosome is copied by an enzyme called DNA polymerase Explain why copying errors are random with respect to fitness Explain why the mutation rate during copying is a heritable trait that is subject to natural selection 21 We compared Biol 80 grades of individuals who work for pay 210 hours per week to grades of individuals who work for pay lt10 hours per week A I test reports apvalue of 00003 Group Mean Standard error n 30 Work lt10hrswk 277 005 324 Work 2 thrswk 248 006 243 Mean Graph the data using the axes provided course grade What does the pvalue from the I test represent 20 lt10hrswk 2 l 0hrs wk Amount of work for pay Give an interpretation of the data and statistical test What can you infer 22 Define evolution 23 Recall the derivation of the HardyWeinberg principle You observe genotype frequencies of PP fl Pp fl and pp f3 What is the frequency of P Suppose you measure allele frequencies of frE1 021 frE2 066 ME 013 You ve also established that genotype frequencies at this gene are in HardyWeinberg proportions What is the frequency of the E1E3 genotype What is the frequency of the E3E3 genotype 24 You are studying the relationship between hours worked for pay each week and final grade in Biology 180 and do a linear regression analysis What do the following results mean Slope 015 R2 018 p 0003 25 In most or all organisms certain genes code for enzymes that repair damaged bases or quotmismatched base pairs eg AG or CA pairs in DNA Why could mutations in the structural sequences of these genes affect the mutation rate Why could mutations in the regulatory sequences of these genes affect the mutation rate 26 In humans an allele called A32 protects individuals against infection with HIV A32 is a lossoffunction allele and is recessive Under selection will its frequency change faster or slower than if it quot 39 t Priorto the evolution of HIV A32 was at relatively high frequency in Denmark In that countw HIV infection rates have been extremely low and are trending lower overtime Predict howthe frequency of A32 is changing in Denmark currently and explain your logic 27 For 100 years researchers selected an experimental population of corn maize plants for production of higher protein content in kernels Their data are plotted below At generation 100 the average protein of a kernel was MUCH higherthan any protein recorded in the population at generation 0 How is it possible for selection to produce quotnewtraitsquot in this way protein kernels 2r namlsmuwswam mnsmumnsmuim 0n the graph add a line predictingwhat happened when researchers removed some individuals from the experimental population at generation 50 and used them to start a new population that was continuously selected for low protein content in kernels Sample answers to additional questions 7 Yes and no Yes because the RNAs produced by these genes are the final product no protein is produced No because information flow is in the same direction as claimed by the central dogma from DNA to RNA 8 Most people with the Huntington s disease allele have already reproduced by the time the disease occurs Their fitness is lower than individuals without the disease because they die in their 40s and cannot continue to help their children and grandchildren as they age but their fitness is not zero 9 No if a cell receives a single copy ofthe normal allele and becomes heterozygous it should produce enough normal product to produce the normal phenoty e 10 It means that the effects of each allele at different genes add together and sum to give the phenotype the genes do not interact in complex ways 11 It is certain that genes consist of stretches of DNA that code for a product along with the regulatory sequences that control when the gene is expressed and in what amount It is uncertain whether the definition of a gene should include all of the sequences that affect its expression and all of the sequences that contribute to its product 12 a Mutation creates new alleles or chromosomes or types of chromosomes selection is the primary reason that those alleles increase or decrease in the population b The new alleles created by mutation have random changes in the DNA sequence meaning that changes in the gene product are random with respect to fitness But under natural selection only alleles that increase fitness increase in frequency in a population This is nonrandom 13 Because deleterious recessives are rare most occur in heterozygotes Few copies of these alleles are in homozygous individuals who are affected by eugenic measures Thus allele frequencies will change slowly if at all 14 Individuals within species are variable at polygenic characters due to mutation creating new alleles and recombination and independent assortment shuffling them into new combinations creating an array of phenotypes Because mutations occur during every meiosis all traits are variable all the time 15 Both The coding sequences would have to be present to produce a normal product and cure the disease The regulatory sequences would have to be present to make sure that the gene is expressed at the right time and in the right amount No to produce normal offspring the cells that undergo meiosis would have to contain normal alleles 16 The basic model is that many alleles are present at the many genes that affect these traits that each allele adds a small amount to the phenotype and that different alleles add different amounts When this is the case then independent assortment and recombination will shuffle the genes and alleles into random combinations and after outcrossing most individuals will end up with a genotype consisting of alleles that produce a moderate or intermediate amount of the trait with fewer having genotypes with alleles producing a small or large amount of the trait 17 It is involved in speech perhaps even required The mutation may have been important in the origin of speech in humans This is not accurate Mutations are random and do not occur in response to need 18 More frequent people with Huntington s disease can reproduce while individuals with the earlyacting allele cannot Less frequent an autosomal recessive can exist in heterozygotes without being eliminated by selection this is not possible in an autosomal dominant 19 Round eyes Almond eyes Wavy hair Straight hair Lighter Darkerskin skin Taer Shorter Black hair Reddish hair Halfthe time the chromosome with the round eye allele will end up in a gamete be transmitted with the chromosome containing the reddish hair allele 20 The enzyme just makes mistakes at random the incorrect base is equally likely to be any ofthe 3 wrong ones It is not possible for the enzyme to preferentially make only certain mistakes that reduce or increase fitness Among individuals there will be variation in the structure and accuracy of DNA polymerase based on variation in the gene for DNA polymerase These variations are alleles that are copied and passed on to offspring and that can increase or decrease in frequency in response to selection depending on whether a higher or lower mutation rate is favorable in the current environment 30 Mean course grade 20 lt10hrswk 210hrswk Amount of work for pay Sample answer See graph The probability of observing this large of a difference between the groups by chance m eaning ifthe null hypothesis of no difference is correc On average students who work forpay less than 39 grades in quot39 m w n 10 or more ours per week 22 A change in allele 39equencies 23 f1 12 f2 0055 2 s h urs worked for pay increase nal grade in Biology 180 decreases Variation in hours worked for pay each week explains 18of the variation in nal grade By chance there is only a 03 probability of seeing a relationship this strong between hours worked for pay and nal grade 25 lfthe altered enzymes are not as ef cient at repairing damage or mismatches the mutation rate would go up lfthe alte are more ef cient at repairing damage or mismatches the mutation rate would i If the enzymes are produced at the wrong time in the wrong amounts or in the wrong types of cells then the mutation rate would increase Likewise 39 quot time o 39 39 or in the cells most affected b dama e or mismatches then mutation rate should decline 26 slower No change if it was at high frequency before and there is little to no selection in favor of it because infection rates are almost 0 the allele frequency should not change much if at all 27 S Avg protein kernels a ainIannmunlswssmnmnnasmnvm Mutation will continually produce new alleles and independent assortment and recombination will continually reshuf e exis in quot 39 39 39 39 In this case quot quot 439 quot 39 39 quot vore rquot r L quot 39 associated with high proteinoil content The combination of selection and continuous production ofheritable variation can result in the evolution of new traits Biology 180 Week 9 10 Study Questions Autumn 2011 Does these questions with your study group 4 people Follow these rules Everyone must participate in every question that you work on Listen to each person 5 contributions At least once during each study session each group member should respectfully challenge another member s ideas Assign roles If your group isn t part of a large session at CLUE or Tribeta or the IC one person should serve as timekeeper39 one as organizer keeping people on task and getting a consensus on when to move on to the next question for discussion one as groupdynamics checker making sure everyone is heard one as challenger making sure that all ideas are carefully considered Format 1 Each person should write answers to the first 4 questions individually in 20 minutes or less these questions would be worth about 35 points on an exam 2 Discuss each question 3 minutes each 3 Exchange papers and use the answer key on p3 to grade each other for full credit partial credit or no credit 1 minute each 4 Each member of the group should write 2 exam questions based on key concepts from this week identified in your weekly notes summary Use these questions to quiz each other 1 In Central America an ant species lives inside the thorns of Acacia cornigera trees A cornigera leaves secrete a sugary solution and make proteinrich structures that the ants eat Design an experiment to test the hypothesis that the relationship is mutualistic specifically that ants reduce herbivory on A cornigera by attacking caterpillars NOTE the final won t include questions on mutualism but it will include questions on experimental design Experimental setup Make and label a graph showing the results Make and label a graph showing the results predicted under the mutualism hypothesis predicted ifthe relationship is actually parasitic 2 Population dynamics equations that may be helpful Nt NO x1 r 111k lnNtN0 rt a A small prairie flower is believed to be declining in abundance In a survey of this flower species 20 years ago 3000 individuals were found This year only 2300 individuals were present Calculate 7 as an annual rate showing your work b An organization called IUCN developed criteria for listing species as critical endangered or vulnerable Their criteria based on population declines are as follows Critical gt20 decline in 2 years Endangered gt5 decline in 5 years Vulnerable gt1 decline in 10 years Based on the lambda you calculated above how would you categorize the prairie flower Explain your reasoning or show your work 3 Consider the population pyramids for the United States given here 0 On the 2000 data label the area that conforms to the quotbaby boomers 0 On the 2000 data label the area that conforms to the quotbaby boom echoquotmeaning the children of baby boomers 0 Examine all three graphs Is the sex ratio proportion of males versus females roughly the same or very different for children under 5 Is the sex ratio the same or very different for adults over the age of 65 0 Examine the number of young children being added to the population in 2000 2025 and 2050 Based on these data is the US population growing quickly because of increased birth rates 0 A comparison of the 2000 2025 and 2050 graphs indicates that the US population is expected to increase rapidly Will most of this growth be due to increases in birth rate or immigration United States 2893 mLE FEmLE 2 d d 439 Population 1n mllllunS uni ed states 2325 l HHNNiAuAAmmn mum amaulaui uiauleui gtQO xz 39wik k ie re f llllll m 39 4 2 o o z 4 Pupuiaum m mlhms 4 One hypothesis for a positive relationship between plant species richness and production is resource use efficiency Each species acquires and uses resources slightly differently so they can all continue to do well in the presence of others In testing this hypothesis would you expect the relationship between plant species richness and production to differ if each additional species is in the same vs different functional groups Answers to questions 14 1 Comparison acacia trees with and without ants the trees with and without ants must be selected randomly so that on average presence of ants is the only thing that differs between treatment groups Then expose trees to equal numbers of caterpillars or iftreatments are randomized you can simply watch natural caterpillar activity and record something relevant to the hypothesis eg amount of defoliation number of caterpillars attacked average time spent feeding per caterpillar acacia seed production or growth etc avg avg biomass biomass of host of host plant plant with without with without ants ants ants ants 2a 2300 3000 73 73 23003000 0767 7 0986 b The population is declining at a rate of 2 per year According to the IUCN criteria it should be considered an endangered species 7 nun1 sum mm mm mm Babvboomers Babyboomecho zonz1o aizooiosa1bxz1 MALE rmz El 0 About the same at early ages but then heavily femalebiased late in life 0 Somewhat but no dramatic or sustained increase in number of newborns 0 Immigration changes in birth rate can t explain increase 4 Production should increase with species richness if species are in different functional groups but show no increase if added species are in the same functional group Additional questions 5 A flowering plant called lupine became established on Mount St Helens soon after the recent eruption a The population grew quickly at first With time however population size began to level off eventually it stabilized Draw a graph that describes the growth trajectory of this population Label the parts of the graph that correspond to the initial phase of rapid growth the phase where growth slowed and the phase where population size stabilized Pop n size Time gt b State a hypotheses to explain why population growth slowed Outline a descriptive or experimental study that would test your hypothesis 6 Define carrying capacity Is the concept of carrying capacity relevant to human populations Provide an argument on both sides ofthis question 7 Compare and contrast the population growth parameters rand 7 How they relate to different types of interest rates on savings accounts 8 You39ve been put in charge of monitoring the sole remaining population of an endangered plant species When the 9 population was initially discovered 25 years ago only 89 individuals remained Since the area was fenced off to prevent grazing by goats the population has increased to 240 individuals During this interval what was I lfthis r is sustained how long will it take the population to double from its current size lfthis r is sustained how long will it take the population to reach 2500 individuals Greenhouse experiments suggest that if populations were introduced to areas with better soil r could be tripled If so how many individuals will exist after 15 years if 50 individuals are introduced to an area with ideal soils Consider the geographic structure of natural populations What is a metapopulation When biologists first explored the dynamics of metapopulations it was out of purely theoretical interest But now the topic is considered of urgent practical importance Why In terms of metapopulation dynamics why is it important to save unoccupied habitat and construct wildlife corridors between habitats used by endangered species Plant biomass gmz A number of hypotheses have been proposed to explain why biomass production increases with increasing species richness State which hypothesis is supported by the data in each ofthe graphs below In each case briefly explain why the hypothesis is supported 200 m n u 160 v 5 E no i E r 120 quot g g 90 U 80 g 5 quot E 40 E 706 1 2 A s i4 no 1 A Number of mutualistic fungal species Sp A 59 A Number of functional groups present present Not Present 11 Some flowering plants do not provide a food reward to their pollinators in the form of nectar Instead they attract male pollinators because their size shape coloration and smell closely resemble female pollinators As a species interaction how would you describe this relationship Is it mutualistic Explain your answer I 1 Consider the interaction between treehoppers and ants described in lecture and in the text For each species what costs and benefits are involved in the interaction If some ofthe costs and benefits involved have not been evaluated rigorously yet how would you do so Is the relationship always mutualistic Why or why not 13 Consider the interaction between clover which fixes nitrogen and arugula which does not How would this interaction change in habitats where nitrogen is abundant in the soil versus rare 14 These Douglas fir population pyramids are from 3 sites one that was logged and replanted to Douglas fir one where succession has been allowed to occur naturally Douglas fir is a mid to latesuccessional species and an old growth forest Identify which graph is from which site In each case explain your logic NOTE the width of the bars indicates that relative abundance of each age class Age classes are in years 700 60 600 50 50 l I 500 40 40 400 30 30 300 20 20 200 1 0 1 00 Site Site Site Logic Logic Logic 15 Consider data on succession at three sites in Glacier Bay Alaska and the following facts alder is a nitrogenfixer alder facilitates growth of spruce hemlock is shadetolerant hemlock can only germinate on organic soils alder and cottonwood make many small seeds that disperse well Suppose that researchers studied a 4 h site that was exposed by the retreating glacier even more recently than Site 3 Name one species that is likely to be at this site early middle and late in succession Explain your reasoning 16 Oxpeckers are birds that eat ticks and other parasites found on large African mammals To test the hypothesis that the relationship is mutualistic a research team captures and weighs 100 cattle in an area where oxpeckers are abundant and 10 water buffalo in an area where oxpeckers have been removed They remove all ticks and release the animals after marking the experimental cattle with red X s They recapture as many cattle and water buffalo as possible two months later to measure weight change Identify and explain two problems with this experiment a c They redesign the experiment based on your recommendations To the right make bar graphs that Host wt gain show the expected results ifthe relationship is mutualistic start to parasitic oxpeckers sometimes wound their hosts and end of drink blood or commensal meaning that oxpeckers experiment do not affect host fitness lnclude error bars Make a kg total of 6 bars in the bar graph Filled bars treatment with no oxpeckers present Unfilled bars treatment with oxpeckers present 17 Consider pyramids of productivity a Draw a pyramid where efficiency of transfer b Draw a pyramid where efficiency of transfer from 1 producers to 1 consumers is 50 from 1 producers to 1 consumers is 10 8 Dee 39 39 mammal species richness is low G L 39 39 39 39 39 u b uiapn 39 39 Jquot quot is due to loss of competitors and predators of deer mice transmission rate hypothesis is correct Deer l muuse Virulence pupulatiun avg fever size when infected gt Speciesrichness gt Deermuuse pupulatiun density mammalsW 19 Consider population growth M Noequot M Nol 7 e39 EDDD suuu a Graphthe data beluvv an the axestuthe right ADDD Human pupulatiun auuu lrl lEIEIs er milliuns Date 375 mu man 7 a mu lEDEI 1875 mun auuu lBBl BEIEIEI 1899 4mm lEDEI mun l7EIEI man man man For bd show how to set up the problems in the space to the right What wasr 39om 1420 to 1720 What was I 39om19611999 lfthe Irecorded 39om 19611999 had continued in what year would the population reach 12 billion 20 This graph is an alternative wayto show age structure in populations it s a population pyramid tipped on 39 39 le es com 39ne hese Its sIde with ma femal bI d T t a e 39om a sh that breeds from age 3 untIl 2 death The solid line predicts the number oflish that m should be in each age class given the number 0 individuals aged 12 and older 9 What is maximum observed lifespan Pmemar at llsh Circle the interval of time when the population was doing particularly badly 2 Why are there so few 02 year olds compared with the predicted number 21 Consider the importance of species richness Recent work suggests that highly diverse Avg communities are more resistant to invasive invasives species than lessdiverse communities In established the space to the right graph the predicted relationship ifthis is so Suggest a hypothesis to explain the pattern you just graphed Explain your logic Based on results of experiments done to date how will a mass extinction event affect overall biomass production increase decrease no change 22 The food chain on the right occurs in the Pacific Northwest Orcas a When sea urchins were harvested heavily for sushi what happened Sea otters to sea otter populations increase decrease no change Sea urchins Kepgigantic b Orcas almost always function as tertiary or quaternary consumers Humans in contrast feed at brown algae a wide array oftrophic levels If humans were limited to feeding in the food web that includes orcas would humans or orcas have higher total biomass Explain why COZin 2339 atmosphere This a simple version of the carbon cycle in marine environments 1H 1H Draw arrows connecting the compartments lnclude consumers mums 002 given off by organisms during respiration 2 3 co2 in consumers Organic seawater Circle the compartment that researchers hope would material in increase over time and decrease global warming benthos if iron fertilization occurred on a massive scale When 002 dissolves in water it reacts to form carbonic acid as a result the oceans are becoming more acidic The calcium carbonate shells made by many marine organisms do not form as efficiently in an acidic environment How do these observations affect the ability of the oceans to function as a carbon sink 24 The research group that studies Glanville fritillaries quanti ed the degree of homozygosity in an array of populations within the metapopulation Then they followed the fate ofthe populations overtime a When they controlled for population size by comparing only populations of similar size they found that populations that were more homozygous were more likely to go extinct Why would morehomozygous populations be more likely to go extinct 5339 Why did they bother to control for population size in this study 25 To restore forests near salmon streams or in citycounty parks volunteers and biologists start by removing invasive species Then they plant longlived large latesuccessional trees a Why do invasives have to be removed rst Why can t you just plant native species directly b Why plant latesuccessional species Why not early and midsuccessional species Note invasives often come back 26 Evolution by natural selection is not progressive and is not based on mutations or adaptations that occur because they are needed Instead itjust happens Explain why each ofthe following just happenquot Heritablevariation Differential success 270 L thespike in u epidemic Flu does not respond to antibiotics pts disease decline ue to anitation and nutrition lfthis hypothesis is correct add a solid line showing changes in the of the population living in areas with treated water and sewagetreatment systems Note the right axis man 100 w gt 7 clean H10 D aOne hypothesis to explain the data is that infectious d d improvements in s c39Add a dotted line showing what the data would look like AkaaAaal t population were due to the availability of antibiotics Penicillin the rst widely used antibiotic was initially available in 1947 Dwain par yam Mort y me neams pa mum 28 Consider how species richness affects the function of plant communities Researchers planted 15 species of plants in experimental plots then added 1 2 4 8 or 14 species of fungi that help plants obtain nutrients from soil Under the resource use efficiency hypothesis predict how increasing species richness of fungi affected aboveground plant biomass in the experimental plots Biomass 2 m m species of fungi Suppose that in northwest forests the relationship between biomass production and species richness is driven by a sampling effect the presence of douglas fir To the right make a bar graph with standard error bars consistent with this pattern Label both axes Researchers planted 132 plant species in experimental plots let them grow and then in half of the plots chosen at random induced a drought In this graph the open circles and dotted line are from control plots the filled circles and solid line are from drought plots Regression analysis indicates Biomass that the slopes of both lines are not 0 another statistical test indicates that gmm2 the slopes of the two lines are significantly different from each other State the two most important conclusions that you can draw from these data Plant species richness 29 Consider the causes of densitydependent growth and recall that r is defined as per capita per individual birth rate per capita death rate Fill in the following chart 4 cells total by explaining why each ofthe following factors would affect per capita birth rate andor per capita death rates Densitydependent Per capita birth rate Per capita death rate factor Food Predation Food predation in combination 30 Consider human population growth Give one reason why the concept of carrying capacity is not relevant to humans Give one reason why the concept of carrying capacity is relevant to humans Why would increased access to education for girls and women affect fertility rates 31 Considerthe study of life history On average and controlled for differences in body size females from hatcheryproduced salmon populations lay more and smaller eggs than females from wild populations Propose a hypothesis to explain why In some Lacerta vivipara lizard populations females lay eggs in other populations females give birth to live young Design an experiment to test the hypothesis that the difference is genetic Experimental setup What to measure 32 Create a population pyramid for the following populations of western hemlocktrees Note that hemlocks have a maximum lifespan of 500 years with high survivorship at every age class until a rapid decline after 350 years In each case the population size for individuals 050 years old is indicated Population growth had been 0 for Population growth had been 0 The population has been slowly centuries but logging just for centuries but NO reproduction declining due to lower reproduction removed all trees gt200 years old occurred during a 10year drought over the past 200 years 230240 years ago Reproduction then returned to previous levels 500 500 500 450 450 450 400 400 400 350 350 350 300 300 300 250 250 250 200 200 200 1 50 1 50 1 50 1 00 1 00 1 00 50 50 50 Answers to additional questions 5a Pop n Slze Rapid growth No growth population stable Growth slows l Time gt U Hypothesis Amount of food available to each individual declines therefore birthrate declines and death rate increases Experiment Add food Population should increase and remain stable as long as you keep adding food at the same rate 6 Definition The maximum number of individuals that can be supported in a habitat over time Argument for relevance At some point resources must become limiting there has to be a population size at which density affects birth rates and death rates Argument for irrelevance There has been no general densitydependence in human population growth over the past 10000 years In addition carrying capacity is defined by the technology available to extract resources and the lifestyle preferred by the population in question The technology is variable among populations and is constantly changing and the amount of resources demanded varies enormously Hence the concept has no real meaning 7 Similarities Both measure growth rates and they have a simple mathematical relationship Differences r is an instantaneous rate while 7 is a discrete or finite rate 7 is like interest on a savings account that is calculated over a discrete time interval eg annually while r is like interest that is compounded continuously 8 Since we don t know the birth rate and death rate we have to estimate r by calculating 7 240 89 73 Thus 7 104 and r 004 Here N0 240 N 480 and r 004 so t 1733 years Here N0 240 N 2500 and r 004 so t 586 years Here N0 50 r 012 and t 15 years so N 3025 9 o A population of populations meaning a group of relatively small and geographically isolated populations Humans are fragmenting many natural habitats and thus forcing organisms into a metapopulation structure Unoccupied habitat Needed so that individuals can colonize new sites and start new populations Wildlife corridors Needed so that individuals can move from one population to another gene flow will reduce effects of inbreeding an drift in isolated populations 10 Left These data support the complementary niche resource use hypothesis based on the assumption that species in different functional groups use resources in different ways Center These data support the sampling effect hypothesis The presence of species A has a huge effect on overall biomass production Right These data support the facilitation hypothesis The presence of more mutualistic fungal species results in increased biomass production 11 It is not mutualistic it is parasitic The angiosperm gets a fitness advantage via pollination while the pollinator suffers a cost wasted time and energy with no nutrient reward 12 Treehoppers cost nutrients lost in honeydew Treehoppers benefit protection from spider predation Ant cost time and energy and risk in attacking spiders Ant benefit access to honeydew nutrients The cost of producing honeydew is assumed and not documented This is difficult to do l think you d have to find mutant treehoppers that do not produce honeydew and compare their fitness to individuals that do when all other conditions are identical and no ants are around The benefit to the ants is assumed to document this you could create artificial treehoppers and provide honeydew solutions with normal versus reduced sugar concentrations and follow ant fitness The cost to the ants is assumed to document this you d have to record ant fitness in the presence and absence of spiders No If spiders are not present there is no measurable fitness benefit to the treehoppers 13 If nitrogen is abundant then arugula would receive so little nutritional benefit from the presence of clover and this benefit could be outweighed by competition with clover for sunlight or water If so then instead of being facilitated it would be inhibited 14 Site natural succession Site logged amp replanted Site old growth Logic Lo i Logic g c Natural seeding in of Simultaneously planting will Old growth should be dominated Doug fir would lead to produce one large age class by extremely old trees Increased population size 15 Species present Logic Early stage Alder is a nitrogenfixer so thrives on bare nutrientpoor soills Alder Alder has small seeds so disperses well cottonwood Cottonwood has small seeds so disperses well Alder comes in early everywhere else Middle stage Spruce Spruce is present at middlelate stages everywhere else Cottonwood Spruce is facilitated by alder Alder Cottonwood has small seeds and disperses well Alder is still present from early succession Late stage Spruce Spruce is late successional everywhere else Cottonwood Spruce is facilitated by alder Alder Alder is still present from early succession Cottonwood is still present from early succession 16 Cattle are marked but water buffalo are not might affect their behavior in a way that influences oxpeckers ticks or weight gain Should mark individuals in both treatments Using so few water buffalo will make it difficult to evaluate the result larger sample would be better Note that imbalance in numbers between treatments is OK statistical tests account for this Having treatment groups in different areasenvironments is bad could affect rate of parasitism by ticks andor weight gain by hosts Using different species in treatment groups is bad could affect rate of weight gain not comparable or frequency of parasitism by ticks or oxpecker behavior NOTE there were other legitimate possibilities Should be highest Should be lowest c They redesign the experiment based on your recommendations To the right make bar graphs that Hostwt gain show the expected results if the relationship is mutualistic start to parasitic oxpeckers sometimes wound their hosts and end of drink blood or commensal meaning that oxpeckers experiment do not affect host fitness lnclude error bars Make a kg total of 6 bars in the bar graph Filled bars treatment with no oxpeckers present Unfilled bars treatment with oxpeckers present Mutualistic Parasitic Commensal 17 18 Deer Arulen ce population avg fever size when infected Species richness gt Deer mouse population density individualskmz b 0002 5 0018 d 2037 20 36 years rummage m m l u A1618 20222426283032 3436 Auemyeais any fewer 311 year olds are breedingthan expected 21 Avg invasive Established Species richness gt D quot quotquot39 39 re uulLe are available for invasives to exploit NOTE be alive for other legitimate alternative hypotheses se c decrea 22 a decreasedepress h L39 L total biomass ucuau e urey quot39 39 39 39 pluuuLe 39 and secondary consumers 23 CO 7 2 atmosphere 1 2 nsumers urnducers gt z 3 consumers seawater It will 39 39 quot 39 39 39 39 L 39 39 39 as shells and raining down into the benthos Lower average tness due to inbreeding depression Smaller populations are more likely to go extinct irrespective ofgenetics tness due to chance events 25 If native species were planted directly the invasives would outcompete them because the invasives are already established an pei39ui r 39 r quot quot39 due to lack u 39 Th 39 t 39 species grow larger 39 39 quot shade them out outcompete them once the natives are established 26 Mutation is random with respect to tness and occurs constantly Some alleles are favored in certain environments 27 mm Mortality me nemns per mama pncipln Dav your Biomass Emml Biomass gmm wo doug wdoug firsspruce firsspmce a species of fungi In both control and drought plots biomass increases with increasing species richness ln droughtplots quot39 39 39 39 39 r 39 39 39 precipitation 29 a iiuue in plotswith normal Densitydependent Per capita birth rate Per capita death rate factor At high density females have fewer Starvation lack of food can kill individuals Food offspring either fewer babiesevent or outright higher time interval between breeding ecause their nutritional status is poorer due to competition More individuals are killed at high density Predation because predators are more ef cient or more abundant if predator populations increase Lack of food can weaken individuals and make Food predation them more susceptible to predation in combination 30 Humans use technological advances to change the carrying capacity of the environment OR Carrying capacity depends on what humans perceive as an acceptable lifestyle At some points resources will run out or be limiting and can t be substituted eg petroleumbased fertilizers and pesticides land soil water Women usually delay reproduction until their education is complete resulting in fewer offspring per lifetime OR If women have the skills to acquire resources on their own they usually invest more resources in fewer offspring 31 In the wild selection is much more intense and larger offspring survive betterthan smaller offspring Raise females from both types of populations in an identical environment either in the lab or in a common garden same location in the wild What to measure Whether offspring are released as eggs or delivered as hatchedlive young 32 In hatcheries the environment is so benign that almost all offspring hatch and survive regardless of quality egg size 500 500 500 450 450 450 400 400 400 350 350 350 300 300 300 250 250 250 200 200 200 1 50 1 50 1 50 1 00 1 00 1 00 50 50 50