Bil160 Ch 22-23 notes
Bil160 Ch 22-23 notes BIL160
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verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
Popular in Biology
This 17 page Class Notes was uploaded by Elizabeth Hernandez on Saturday January 31, 2015. The Class Notes belongs to BIL160 at University of Miami taught by Dr. Sarkar in Fall. Since its upload, it has received 44 views. For similar materials see Biology in Biology at University of Miami.
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Date Created: 01/31/15
Ancient Bodies Modern Lives 13115 658 PM Ancient Bodies and Modern Lives Arthritis Gout uric acid build up in joints UA is an antioxidant takes out oxidative radicals CAunregulated cell growth Humans are living longer more than 30 or 40 years Cell mechanisms haven t evolved to live so long In addition to carcinogens Spontaneous miscarriage and MHC If MHC s are similar baby will miscarriage Bc baby doesn t have a variety of immune specific genes Menstruation no implantation Layers that form in endometrium will shed Maintaining that lining is more costly to the human body rather than making a new one Autoimmune disease incidents are increasing DM Asthma lupus RA Ancestors evolved in dirty places Immune system was built to fight those pathogens NOW we have antibiotic agents TOO CLEAN Immune system is forgetting to recognize self and non self Its instinct is to attack attack attack HIV and STD39s capacity to infect other cells is becoming more virulent It doesn t care to take care of host WHY Our way of life Promiscuity several sexual partners Providing too many drugs drug cocktailquot If you don t provide any drugs to HIV pt the virus eventually regresses to original nai39ve form Why Evolutionary pressure is gone so the virus doesn t use it s energy to be so virulent Osteoporosis Ca is dissolved in water so that s how it was absorbed We moved from aquatic environment to terrestrial Our body s hormones also stop metabolizing Ca Schizophrenias creative families artists musicians have more schizophrenic members Genes for creative traits go a little bit off and they begin to hallucinate Eye problems glasses our eyes have not evolved to see up close they are made to see far away for hunting purposes Lactose Intolerance mutation in lactase gene Most European population can digest lactose but not Asian Native Americans cannot digest it either Lactose intolerance is the normal gene but in the European population they mutated a gene and started being able to drink milk Breast CA in women in developing countries Women have more children in LDC During pregnancy and lactation is a natural form of birth control Breast cells are not exposed to changing levels of hormone levels in body In developed countries don t want to have as many babies During estrogen cycle there is a change in hormone levels Breast cells don t like the changes Jaundice hepatitis Yellowing of eyes and skin Build up of bilirubin which is a product of hemoglobingt biliverdin harmful to our bodygt bilirubin Bilirubin is a very good antioxidant remove oxidative radicals that make cells age faster Blood cells recycle every 120 days If you have liver disease the liver can t break down bill as well and that s when you get yellow FluMalaria the cold virus you don t feel good but you can walk around The virus wants you to walk around so that you can spread the disease Malaria on the other hand makes you SO SICK that you can t even kill the mosquito So then it goes around and infects others Allergies Immune system is not able to differentiate self and non self Same as autoimmune Depression and Anxiety Body preparing for disasteremergency EG dying event In some individuals it is too much Sometimes people with anxiety survive better Timid ones hide and survive aggressive ones die Not doing anything sometimes is better for survival Crying Babies five siblings one baby cries all the time Baby s cry to gain attention survival Grandparents pass on experience to help children and grandchildren to survive better Descent With Modification 13115 658 PM Creationism God created all organisms therefore all organisms are perfect They cannot evolve Order is created by God Do not accept evolution Intelligent Design modern form of creationism Don t actually name God but all of the organisms are designed intelligently E6 the heart evolutionary biologists say that the chambers of heart have been added slowly ID believe that heart came as a whole created by a force E6 the eyes need every part to have a functioning eye ID believe that it came as a whole Our eye is not perfect we have a blind spot EG blood clots blood needs a clotting cascade did not come as a whole blood clot system Figure 222 know how Darwin developed things and how ideas influenced him to develop evolutionary theory Darwin studied Hutton Principle of Gradualism earth expresses changes gradually due to events Lyell publishes Principles of Geology geologic events happened thousands of years ago and are still getting modified today Also studied Lamarck 1St person to publish on evolutionary change even though his theories were wrong inheritance of acquired characteristics EG you work out the pass muscles to children but at least he accepted change Darwin also studied Malthus Essay of the Principle of Populationquot food increases arithmetically and population increases geometrically When they clash is when there is war and famine because of a lack of resources Cuvier archeologist French creationist Published his studies of vertebrate fossils layers of rock were due to catastrophic events Darwin finally writes his essay on descent with modification Point organism changes in response to environment yr 1844 Lamarck and Darwin s theories are similar but Lamarck said that they passed things down to children use and disuse Darwin explained that some giraffes had different neck lengths that s the nature of population The giraffes with longer lengths had more food so they survived more and reproduced Darwin didn t know about genes chromosomes mutations Natural Selection Wallace those individuals with favoring traits will reproduce and pass on genes DARWIN AND WALLACE Theory of Natural Selection Modern Synthesis Theory Which of the following scientists influenced Darwin s views on the nature of population growth Malthus Improving the intelligence of an adult through education will result in adult s descendants being born with a greater intelligence This statement is an example of Lamarckism Individuals in a population carry in their heritable characteristicsDarwin Organisms produce more offspring than the environment can supportMalthus Individuals that are well suited to their environments tend to leave more offspring that others AND over times favorable traits accumulate in the population 012015 spore cloudquot organisms produce more offspring than environment can support Darwin noted that humans gave modified other species by selecting and breeding individuals with desired traits a process called artificial selection EG wild mustard has enough heritable variation to create kale Brussels sprouts cabbage broccoli and Kohlrabi Natural selection is a process not the end for change in a population that occurs when organisms for a particular environment to survive reproduce and pass on these traits Natural Selection works at the individual level and evolution works on population level DARWIN AND WALLACE Darwin s fitness the one that leaves the most number of fertile offspring Natural selection leads to adaptation slow changes that occur lead to adaptation to environment that s why we see in environment perfectly camouflaged individual Darwin s focus on Adaptation In reassessing his observations Darwin perceived adaptation to the environment and origin of new species as closely related processes From studies made years after Darwin s voyage biologists have concluded that this is what happened to the Galapagos finches cactus eater insect eater seed eater Natural selection does not create new traits but eits of selects for traits already present in the population on what is available The current local environment determines which traits get selected for or against in and population Natural selection is based on all of the following except the fittest individuals to leave the most offspring the fittest individuals tend to leave the most offspring there is differential reproductive success wihting populations Populations tend to produce more individuals than environment can support The branching pattern explains both unity and diversity bc is gives rise to dif species Both Darwin and Lamarck39s ideas regarding evolution suggest which of the following All species were fixed at the time of creation acquired physical characteristics can be inherited the giraffs long neck is result of artificial selection the the main mechanism of evolution if natural selection Darwin and VVaHace Evidence direct observations homology similarity resulting from common ancestry the fossil record biogeography Direct observation found population changing because of change to environment can be seen with bugs with short lifespan MRSA change to drug resistant population Question on mastering about killfish and bright colored prey Imagine a species of bird in which females prefer Example of evolution in action Daphnia water flee lifespan 3 mo They took eggs of Daphnia from bottom and top of lake Michigan and incubated them A lot of difference in reproductive structures of the flees Anatomical and Molecular Homologies Homologous structures are anatomical resemblances that represent variation on a structural theme MOST IMPORTANT EVIDENCE Molecular Homology genes shared among organisms inherited from a common ancestor cytochrome c oxidase gene then are mapped The more the differences in nucleotides the earlier they split in ancestor tree Comparative embryology reveals anatomical homologies not visible in adult organisms malleus incus and stapes are the bones that supported the clefts Embryos evolve in water embryonic fluid we are still not completely independent of water Imagine two species that are thoughts to have a recent common ancestor If this idea is correct these two species most likely have A no morphological similarities B few biochemical similarities C several homologous structures D similar embryological development Vestigial structures remnants of features that served important functions in the organisms ancestors EG wisdom teeth tail bone hind legs in pythonancestor could walk use appendages to move Vestigial structures are anatomical structures that have no function Homologies and Tree Thinking Evolutionary trees are hypothses about the relationships among dif groups Homologies form nested patterns in evolutionary trees Trees can be made usin gdif types of data EG anatomical and DNA sequence data Convergent Evolution The evolution of similar or analogous features in distantly related groups Analogous traits arise when groups independently adapt to similar environments in similar ways faced a similar evolutionary pressure Convergent evolution does NOT provide info about ancestry Fossil Record Fossil record provides evidence of the extinction of species the origin of new groups and changes within groups over time Carbon dating when you measure how much carbon has decayed to find original amount age C14 carbon dating 500 year half life Transitional fossils have features of two dif groups Archaeopteryx birds that had reptilian features as well as avian Not larger than a chicken Fossils found in China and Germany Found teeth in its beak and vertebral column extends column reptilian feature Also had claws but it was coved with feathers so it couldn t fly very well it glided Whales had pelvic girdle Showed that it walked on land since it lives in the ocean it is a secondary condition Biogeography the scientific study of the geographic distribution of species provides evidence of evolution Lemurs 49 species 100 of species found only in Madagascar Drosophila 800 species only found in Hawaii Only marsupials in America possum unique feature when they re startled their body freezes In a hypothetical environment fish called pike ch are visual predators of algae eating fish Locate prey by size If a population of algae eater experiences predation pressure from pike c which of the following would least likely be observed in the algae eater pop over time Coloration may become drab Become nocturnal Chapter 23 The Evolution of Populations 13115 658 PM The most important missing evidence or observation in Darwin s theory of 1859 is the source of genetic variation Smallest Unit of Evolution Natural selection acts on individuals but only populations evolve indiv Do not evolve populations evolve Darwin s finches They collected data on finches in 1976 beaks were 9 mm then drought came and measured beaks again in 1978 10 mm Genetic variation makes evolution possible Variation in heritable traits is a prerequisite for evolution remember natural selection works on genetic variation Mendel39s work on pea plants provided evidence of discrete heritable units genes Mutations get passed on to offspring through genes which is Modern Synthesis Theory no longer Genetic Variation Genetic Variation caused by dif in genes or DNA segments Phenotype the gene expressed hair color eyes height Controlled by single dimples eye lash length attached ear lobe or multiple genes height eye color Natural Selection can only act on variation with a genetic component of individuals Can be measured as gene variability heterozygote or nucleotide variability change in DNA sequence If nucleotide variability in population is 0 what is type of gene variability in population 0 number of alleles in population 1 Nucleotide variation rarely results in phenotypic variation not always true Diff in Japanese snail shell coiling due to point mutation and they can t mate ONLY ONE POINT MUTATION Some phenotypic variation does not result from genetic dif among individuals But environmental influences Only genetically determined variation can have evolutionary consequences DOES NOT PARTICIPATE IN EVOLUTION Epigenetic Factors beyond gene factors not gene factors Sources of Genetic Variation New genes and alleles can arise by mutation Only mutations in gametes are passed off to offspring Mutations have to occur in exons Neutral variation mutation in noncoding regions may not have any selective advantage Mutations to genes can be neutral because of redundancy in the genetic code Harmful mutations can be hidden from selection in recessive alleles unless it becomes homozygous then person may die and not reproduce Altering gene by gene duplication deletion or position hox genes dictate segmentation where eyes and body appear they show up through entire tree of life Part of gene can get deleted autism part of chromosome 17 falls off because it s very brittle then genes there get lost Recombination sexual reproduction can result in genetic variation by recombining existing alleles Meiosis Prophase 1 is when crossing over occurs in fertilization Sex is important Sexual recombination reshuffling of alleles Asexual reproduction have differences in alleles by mutations In desert its difficult to find mates so females find females and they give forth to pathogenesis females giving birth to females Rapid Reproduction mutation rates higher in viruses so they evolve faster low in animals and plants Mutations accumulate quickly in prokaryotes and viruses bc they have short generation times That s why we don t have any antibiotics against viruses because they mutate so fast Hardy Weinberg equation test whether population is evolving First step in testing is to clarify what we mean by a population gene frequency Allele frequency Genotype frequency given by hardy Weinberg when pop is not evolving Not possible controlled conditions HYPOTH ETI CAL Gene pool the amount of genes that you have to pick from sum of all genesalleles present in population USA has a very rich gene pool Population a group of members of a single species present in a geographical area Should be able to interbreed and produce fertile offspring A locus is fixed if all individuals in a population are homozygous for same allele Populations take time to separate take time to interbreed Conditions for Hardy W HYPOTHEICAL in real populations alleles and genotype frequencies change over time It will give you 5 under ideal conditions CONDITIONS for nonevolving populations no mutations random matingno female choice no natural selection extremely large population size hard to find bc of lack of resources mating etc no gene flow cannot occur bc of immigration and emigration that changes alleles from original population pA2 homozygous dom 2pq heterozygous qA2 homozygous recessive P frequency of Dominant Q frequency of recessive Frequency of A is 055 what will be frequency of a 045 Aa1 Frequency of heterozygotes 495 Genotype frequency of AA pA2 03025 Pop A 36 red 16 white 48 roan What are allele frequencies Total number of alleles in pop is 100x2 200 R r RR 36 x2 72 of alleles in red pop 0 rr 16 0 of alleles in white pop 32 Rr 48 48 of alleles in roan 48 120 total number of alleles 80 120200 6 R 80200 04 r Natural populations can evolve at some loci while in Hardy W equilibrium at otherlocL Small changes in dif loci will get added on and that s how a population changes Natural Selection genetic drift gene flow FORCES OF EVOLUTION 3 major factors alter allele frequencies and bring about most evolutionary change 0 Genetic Drift smaller a sample the greater the chance of random deviation from a predicted result Randomly kills part of population describes how allele frequencies fluctuate unpredictably from one generation to the next RANDOM KILLING OF POP EG earthquake Tends to reduce genetic variation through losses of alleles Bottleneck effect high evolutionary pressure acting on population 0 Gene Flow 0 Natural Selection Gene vs allele allele is same version of dif gene Small population BIG EFFECT if you start with small population and 50 dies there s a chance that it may kill off certain gene Changes amount of gene frequencies potential to lose one or more alleles 012715 Genetic drift could result in bad alleles being fixed in population Hardly no genetic variation in cheetah genes We have been able to increase population bc of inbreeding FL panther were almost extinct In many tribal populations they don t allow their children to marry outside population Afraid that old population will be diluted but genetically they are very weak Inbreeding brings problems With dogs German Shepherds they have problems with vertebral columns other is prone to pancreatic CA Pure bred dogs are genetically weaker Found Effect Occurs when a few individuals become isolated from a larger original population They inbreed among themselves No random mating so no new alleles are coming in EG British population became isolated in a small island The population consisted of only 15 ppl they interbred They mostly all carry retinosa pigmentosa EG Amish community They migrated from Germany settled in NE America and they are very close community They don t use modern technology aren t open to children marrying outside High frequency of neuronal disorders polydectaly and cataracts Allele frequencies in the small founder population can be different from those in the larger parent population Bottleneck is random sudden decrease in population Founder s is separation from community Outcome is the same Effects of Genetic Drift SUMMARY gene variation shifts from original 0 Genetic drift is significant in small populations can cause allele frequencies to change at random can lead to loss of genetic variation within populations can cause harmful alleles to become fixed Gene Flow Gene flow consists of the movement of alleles between populations immigration emigration Ppl migrating from other countries etc when you move out you take your alleles with you Alleles can be transferred through the movement of fertile individuals or gametes EG pollen Gene flow tends to reduce variations among populations over time Is a force of evolution Gene flow can decrease or increase fitness of a population EG decreaseO the Great Tit bird on the clutch island of Vlieland immigration from mainland introduces alleles that dec fitness on the island Natural selection removes alleles that dec fitness EG insecticide on mosquitos Alleles have evolved in pop that confer insecticide resistance Causes an inc in fitness Genetic Drift and Gene Flow do not consistently lead to adaptive evolution as they inc or dec the match between an organism and its environment Sometimes badd alleles come into population Can reduce adaptive nature of adaptive population Dif mechanisms working that s why they have separated these forces Populations evolve differently gene flow genetic drift natural selection Natural Selection Differential reproductive success results in alleles being passed on to next generation in greater populations EG mosquitos who could withstand insecticides survived and reproduced Natural selection is only force in evolution that results in Adaptability Mutations arrive by change Only natural selection consistently inc the frequency of alleles that require reproductive advantage Directional Disruptive and Stabilizing Selection Directional favors individuals at one extreme end of phenotypic range Disruptive selection favors individuals at both extremes of the phenotypic range Stabilizing selection favors intermediate variants and acts against extreme phenotypes Amm see 3 a directional b disruptive c stabilizing Cranial capacity the volume of the skull has increased in hominines over time Directional selection Natural selection increases the frequencies of alleles that enhance survival and reproduction Adaptive evolution occurs as the match between a species and its environment increases Because the environment can change adaptive evolution is a continuous process Sexual Selection natural selection for mating success It can result in sexual dimorphism marked differences between the sexes in secondary sexual characteristics EG humans females look very dif from males disruptive In a population 0 fish body coloration varies form a white to wvery dark shade of green If changes in environment resulted in dec prediction of individuals with lightest coloration this would be an example of Directional Intrasexual within selection is direct competition among individuals of one sex often males for mates of the opposite sex Males fight with other males Intersexual selection often called mate choice Occurs when individuals of one sex usually females are choosy in selecting their mates Male showiness due to mate choice can inc a male s chances of attracting female while dec his chances of survival Natural selection tends to reduce variation but there are mechanisms which maintain variation in population Maintenance of Variation Balancing selection Diploidy most organisms are diploid maintains genetic variation in the form of recessive alleles hidden from selection in heterozygotes Balancing selection occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population Balancing selection includes heterozygote advantage and frequency dependent selection Frequency Dependent Selection the fitness of phenotype declines if it becomes too common in the population EG flu virus enters the body and immune system doesn t recognize only the mutated flu virus That one multiplies Natural Selection cannot be Perfect Selection can act only on existing variation evolution is limited by historical constraints adpatations are often compromises chancenatural selection and the environment interact Origin of a Species 13115 658 PM What is wrong with Hardy W here Some moths on a tree are easier to see due to their lighter color and therefore are eaten by predators more often No selection Male elephant seals show aggression toward other males resulting in dom males mating with several females and other males mating with few or no females Random mating occurring Until 19505 infants born with CF did not survive longer than a few months If the frequency of carriers was 4 in1900 what proportion of CF alleles was eliminated in one generation 2 What is a species
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