Final Study Guide Bio 311D Dr. Bierner 2016
Final Study Guide Bio 311D Dr. Bierner 2016 BIO 311D
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This 42 page Study Guide was uploaded by Liam Murphy on Monday May 9, 2016. The Study Guide belongs to BIO 311D at University of Texas at Austin taught by Dr. Mark Bierner in Winter 2016. Since its upload, it has received 119 views. For similar materials see Introductory Biology II in Biology at University of Texas at Austin.
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Final Study Guide: Bio 311D Lectures 30, 31, and 32: Organismal and Behavior Ecology Vocab: ● Abiotic environment: nonliving ● Biotic environment: living ● Niche: how something lives, what are its needs, is it dependent on something else, etc. ● Ecological time: Key Concepts/ Important Statements: ● Interactions between organisms and the environment limit the distribution of species ● Selection for individual survival and reproductive success can explain most behaviors ● Genetic analyses and the concept of inclusive fitness provide a basis for studying the evolution of behavior ● Species distributions are a consequence of both ecological and evolutionary interactions through time ● One factor that contributes greatly to the global distribution of organisms is dispersal ● The importance of dispersal is most evident when organisms reach an area where they did not exist previously ● To determine if dispersal is a key factor limiting distribution of a species, ecologists may observe the results of intentional or accidental transplants of the species to areas where it was previously absent ● Transplant experiments show that some organisms do not occupy all of their potential range, even though that may be physically able to disperse into the unoccupied areas ● If a behavior does not limit the distribution of a species, the next question is whether biotic factorsother species are responsible ● Because adequate nutrition is essential to an animal’s survival and reproductive success, we should expect natural selection to refine behaviors that enhance the efficiency of feeding ● One of the most significant potential costs to a forager is risk of predation. Maximizing energy gain and minimizing energy costs are of little benefit if the behavior makes the forager a likely meal for a predator. Balancing risk and reward, therefore, also influences foraging behavior ● The needs of the young are an important factor constraining the evolution of mating systems Questions: ● What do we mean by ecological time? ○ Minutetominute time frame of interactions between organisms and the environment ○ What we can observe throughout generations ○ Changes in weather year by year ○ How things are interacting with their environment ○ Selection for beak depth in Galapagos finches ● What do we mean by evolutionary time? ○ Through natural selection, organisms adapt to their environment over the time frame for many generations, in evolutionary time ○ How did something evolve and how is it able to live where and how it does ● How do abiotic (physical rather than biological, not living things) factors affect distribution of the saguaro cactus? ○ It has adapted to dry conditions ○ You can give it too much water and it dies ○ Temperature restricts the distribution ■ North is colder ○ Elevation affects its ability to live ○ Very slow to grow, because seeding requires specific moisture (can’t grow in Baja → bc incorrect moisture amounts ● How do biotic (biological, living things) ○ Pollination factors ○ Interactions with things that eat them ○ Grows in places that certain bacterium is not present ● Look at slide 1317 to see flowchart of factors limiting geographic distribution ● What is dispersal? ○ How something gets from one place to another ■ Could be due to winds, animals, weather, etc. ■ Importance is evident when organism reach an area where they did not exist previously ○ The movement of indiiduals or gametes away from their area of origin or from centers of high population density ○ Critical to understanding the role of geographic isolation in evolution ● What is biogeography? ○ Geographic distribution of living things ○ Why things are located where they are ● Situation with the cattle egret, shown slide? (slide 25) ○ Cattle egret was only in Africa and SW Europe 200 years ago but in late 1800’s they managed to cross Atlantaic and colonize northeastern South America ■ Spread southward and northward ○ Old world bird that spreads out ○ North and south american tips ○ Ability to fly ○ Does not go south american east coast for various reasons ● What is adaptive Radiation?What is the situation with silver swords in Hawaii? (See figure 25.22) ○ Rapid evolution of an ancestral species into new species that fill many ecological niches ○ Hawaiian silverswords is an example of adaptive radiation that was possible only with the longdistance dispersal of an ancestral tarweed from North America ○ Older things in Kauai and younger things in Hawaii ● Successful transplant? ○ The species is able to survive and reproduce sustainably ○ Potential range is larger than its actual range ○ Species could live in certain areas where it currently does not ● What's potential range vs. actual range? ○ Potential: where it could live it could survive there ○ Actual: where the animal is currently surviving ● What are some of the consequences of species transplantations? ○ Species often disrupt the communities and ecosystems to which they have been introduced and spread far beyond the area of introduction ○ Bunnies to western Australia (natural predators keep bunny populations in America, but in Australia there were no natural predators so they ate everything and populated like crazy) ○ They overpopulate and take over the land they are transplanted to ■ Ex: Kudzu plant in southeastern US and rabbits in australia ● Does behavior play a role in limiting distribution in cases where Transplant experiments show that some organisms do not occupy all of their potential range, even though that may be physically able to disperse into the unoccupied areas? ○ Yes, because when individual avoid certain habitats, even when suitable, the organism’s distribution may be limited by habitat selection behavior ● What is habitat selection behavior? ○ Process an animal uses to select or choose a habitat in which to live, they must have access to this habitat, be able to tolerate biotic and abiotic factors, find shelter, food, and mates ● How about the lack of an appropriate host in areas where an insect could survive otherwise? ○ It could survive if there was an appropriate host for it (maybe an insect or parasite), but without host-it couldn’t survive there ○ Insects often deposit eggs only in response to a very narrow set of stimuli, which may restrict distribution of the insects to certain host plants (larvae of European corn borer are found exclusively on corn ● If behavior does not limit the distribution of a species, the next question should be whether biotic factors/other species are responsible ○ Always a possibility ● How might interactions with predators or herbivores restrict the ability of a species to survive and reproduce? ○ Negative interactions with predators or herbivores restrict he ability of a species to sruvive and reproduce ○ If it gets eaten, it won’t survive ○ They could evolve and adapt to survive in the presence of the predator (adaptive radiation) ● What’s the deal with sea urchins (herbivores) limiting the distribution of food species (seaweed) → slide 44 ○ Both present = little seaweed covered ○ Both removed = a lot of seaweed covered; greatest increase in seaweed cover ○ Only urchins removed = seaweed still grows ○ Only limpets removed = little seaweed covered ○ Big herbivore is the sea urchin, because the biggest impact (increase) of sea weed coverage happens when they are removed ● How about other biotic factors such as presence or absence of pollinators, food resources, parasites, pathogens, and/or competing organisms? ○ act as a biotic limitation on species distribution. ■ Ex: when humans accidentally or intentionally introduce exotic predators or pathogens into new areas and wipe out native species ● What’s the situation with temperature? (an abiotic factor as a limiting species distribution) ○ Affects biological processes = cells with water may rupture at freezing temperatures ○ Enzymes have optimal temperature that they function in = most denature when temp is above 45 degrees celsius ; cells may rupture at freezing temperatures ○ Must be able to tolerate a certain temperature range, temps outside the range would force some animal to expend energy regulating their internal temperature as mammals and birds do ○ Thermophilic prokaryotes = allows living outside the temperature range habitable by other life ○ Thermal pools ● What’s the situation with water and oxygen? What problems might the Paedophyryne frog face? ○ Variation in water availability among habitats is another important factor in species distribution ○ Species living at seashore or in tidal wetlands can desiccate (dry out) as the tide recedes ○ Terrestrial organisms face a nearly constant threat of desiccation ■ Distribution of terrrestrial species reflects their ability to obtain and conserve water ○ Oxygen is taken in via skin, so if it gets dried up, they suffer ○ Tender skin frog won’t be able to survive and get oxygen through skin ○ Restricted to moist areas as their habitats ○ Harlequin toad are vulnerable to drying because they use their moist skin for gas exchange ○ Water affects oxygen availability in aquatic enviornments and in flooded soils ○ Because oxygen diffuses slowly in water, its concentration can be low in certain aquatic systems and soils limiting celluloar respiration ○ Oxygen concentrations can be low in deep waters and sediments where organic matter is abundant ○ Mangroves and other trees have specialized roots projecting above water to help obtain oxygen ○ Surface waters of streams and rivers tend to be well oxygenated ● What’s the situation with salinity? ○ Osmoregulators can survive conditions of salt/fresh water ○ Halophytes-salt lovers (succulents) ○ Aquatic animals restricted to fresh or saltwater habitats by their limited ability to osmoregulate ○ High salinity habitats have few species of plants or animals ● What’s the situation with sunlight? How about at high elevations? Might temperature also be a factor? ○ Sunlight absorbed by photosynthetic organisms provides the energy that drives most ecosystems, and too little sunlight can limit the distribution of photosynthetic species ○ photosynthesis in aquatic environments occurs relatively near the surface, because sunlight does not reach lower ○ Too much light can also limit the survival of organisms. ○ At high elevations, the sun’s rays are more likely to damage DNA and proteins because the atmosphere is thinner, absorbing less (UV) radiation. Damage from UV radiation, combined with other abiotic stresses, prevents trees from surviving above a certain elevation, resulting in the appearance of a tree line on mountain slopes ● What’s the situation with rocks and soil? ○ pH, mineral composition, physical structure of rocks and soil limit the distribution of plants and animals contributing to the patchiness of terrestrial ecosystems ○ Is there enough soil for the plants to get their roots into? ○ Consider pH of the soil ■ pH of soil can limit the distribution of organisms directly, through extreme acidic or basic conditions, or indirectly, by affecting the solubility of nutrients and toxins ○ In a river, composition fo the rocks and soil that make up substrate (riverbed) affect water chemistry influencing resident organisms ■ Structure of the substrate determines the organisms that can attach to it or borrow into it ● What all does foraging include? ○ eating the food, searching for it, recognizing what is good food, and capture food items ● What does the gene called forager (for) control? What is the for allele? What is the for S allele? ○ Forager (for) dictates the food search behavior ○ ForR: rover = wander further out looking for food twice as far as ForS ■ Enzyme encoded by forager locus is more active in forR than in forS ○ ForS: sitter = do not move around as much as a rover ○ Both forR and forS are prsent in natural populations ● What happened in the low population density lines? (Slide 63) ○ Move less distance, because less competition taking the food that is close ○ forS allele increased in frequency in low-density population ○ Short distance foraging yields sufficient food, while long distance foraging is unecessary energy expenditure ● What happened in the high population density lines? (Slide 64) ○ Travel farther, because more people to compete with ○ forR allele increased in high density ○ Long-distance foraging enable larvae to move beyond areas of food depletion ● What did the researchers find when they looked at the frequencies for the for and for S alleles? ○ Frequencies refers to percentages ○ Low density-Sitter allele most prevalent ○ High density-Rover allele most prevalent ○ Sitters don’t move a lot, rovers move farther ● How did you explain that? ○ Low density-more food available, less competition, don’t go as far ○ High density-more competition for food in area, advantage is to go farther and find more resources ● What is a cost-benefit analysis? ○ Overall costs compared to the benefits ‘risks compared to return’ ● What are the benefits and costs of foraging? ○ Getting your food, water, nutrients ○ Energy expenditure to traveling and risk of being eaten ● What is the optimal foraging model? ○ Natural selection shold favor a foraging behavior that minimizes the costs of foraging and maximizes the benefits ○ least amount of cost for the greatest benefit ● What is the situation with feeding behavior of the Northwestern crow on sea snails called whelks? ○ Crows grab a whelk and then drop them, hit the rocks on the coast until shell cracks, then they eat the inside of the shells (fucking savages) ○ Consider how high they must fly up, how much energy they need, how many times to drop it ● How did the researchers determine the optimal height for dropping whelks that resulted in breaking the shell with the least work? ○ Started off at a particular height: then kept going until they found a drop height (5 meters) that resulted in the smallest amount of flight height and average number of drops = resulted in the smallest amount of energy being used ● What was that optimal height? What was the drop height preferred by the crows? What did these results suggest? ○ 5 meters, preferred by crows was 5.23 meters = figured that out by their expended costs and they had the greatest chance of survival so they could reproduce at higher rates and passed this along to future generations ○ Suggest: this a product of evolution, selection, and fitness ● What is the situation with regard to food availability for mule deer? Where is the risk of predation from mountain lion the highest? How does mule deer foraging behavior reflect the differences in predation risk in particular areas? ○ Food availability highest in the forest ○ Risk of predation is the highest in the edge of the forest ○ Forest ones die, but get more food ○ Meadow ones live, but get less food = the ones that make it farther because they live and pass along their traits and can reproduce ○ Mule deer feed predominatntly in open areas showing that foraging behavior reflects the large variation in predation risk and not the smaller variation in food availability ○ This result underscores the point that behavior typically reflects a compromise between competing selective pressures ● What is a promiscuous mating system? ○ No strong pair-bonds ○ One with multiple sex partners, like ut students ● What is a monogamous mating system? ○ One mate (slide 82, the birds) ● What is a polygamous mating system? What is polygyny? What is polyandry? ○ Polygyny: single male with many females, male must be able to attract multiple females (slide 83, the deer) ○ Polyandry: one female with multiple male partners, females are more highly ornamented, must attract males by a certain quality (slide 84, more birds) ● Sexual dimorphism? ○ Two sexes look different, look at slides 82-84 for this ○ Monogamy - both look identical ○ Polygyny - males are showier and larger ○ Polyandrous - females are more ornamented and larger ● Why are most birds monogamous? ○ Baby birds are helpless when hatched, someone needs to take care of them, shared parental care increases reproductive success since more chicks survive when mom and dad protect them ● When does polygyny tend to occur in birds? ○ If the benefits of having more ‘mistresses’ for the male bird outweighs the benefits of sticking around and raising the chicks ○ Birds with young that can feed and take care of themselves; males have less benefit of staying with partner so they maximize their reproductive success by seeking other mates ● What’s the deal with many mammals? What about when males protect the females and young i.e. lions? ○ Lactating females is only food source for the young; males usually play no role in raising the young ○ In mammalian species where males protect the females and young (lions), male or small gorup of males tytpically takes care of a harem of many females at the same time ○ Care of the young have longer care time, nutrition comes from mother ○ Unless there’s an advantage for the males to stick around, they’re going to go off and hook up with other females ● What’s the deal with certainty of paternity? ○ If you know it’s your kid, you’ll put in more effort to take care of them ○ Relatively low in most species with internal fertilization because the acts of mating and birth are separated over time ○ Males of many species with internal fertilization engage in behaviors that appear to increase certaintiy of paternity; behaviors of ■ Guarding females ■ Removing sperm from the reproductive tract ■ Introducing large quantities of sperm ○ Certainty of paternity is high when egg laying and mating occur together as in external fertilization ● What is sexual selection? ○ natural selection arising through preference by one sex for certain characteristics in individuals of the other sex ● What is intersexual selection versus intrasexual selection? ○ Intersexual selection:females choosing from males based off of preferences ○ Intrasexual selection: competition, the victor gets to mate with the female if he wins the duel ● How about courtship involving female mate choice of males with longer eyestalks? ○ Males with longer eyestalks are chosen by females ‘bigger is better’ ● What did the experiment show? (Influence of imprinting on mate choice) ○ Females raised by an ornamented male parent preferred ornamented males as their own mates ■ Female finches apparently take cues from their fathers in choosing mates ○ Normally the males and females don’t have crests ○ Looking at the female offspring preferences ○ If female is ornamented then they want a ornamented male ○ Mixed offspring: do not prefer ornamented (NO preference) ○ Some sort of learned behavior is going on ● What is mate choice copying? ○ No competition on the top, so they have a choice of all males = prefer the one with the most color ○ In the bottom when a fake is going after the least colored male, then the female now chooses the one she never would have before because of jealousy? ○ Female that mates with males that are attractive to other females increases the probability that her male offspring will also be attractive and high reproductive success ● What is agonistic behavior? ○ Outcome determined by strength or size ○ Competition among males for the female ■ Ex: male kangaroos fighting for the female, winner gets the “prize” ● SKIP: Section applying to game theory ● Let’s take a look at the courtship behavior of male fruit flies. Genetic studies have revealed that a single gene called fru controls this entire courtship ritual. ● What happens if the fru gene is mutated to an inactive form? ○ Males do not court or mate with females ○ If it happens in males: they do not do the ritual ● Normal male and female flies express distinct forms of the fru gene. What happens if females are genetically manipulated to express the male form of fru? ○ Females act like males ● How can a single gene control so many behaviors and reactions? ○ It doesn’t code directly for behavior, it codes for transcription factors that in turn control other genes that have to do with the mating behavior and turns on a lot of genes ● What type of gene is the fru gene? ○ Master regulatory gene that directs the expression and activity of many genes with narrower functions ○ genes that are controlled by the fru gene bring about sex-specific development of the fly nervous system ● What is it that genes controlled by the fru gene actually do? ○ In females, controls genes involved in development of nervous system that have to do with female behavior and vice versa ○ Fru programs the fly for male courtship behavior by overseeing a male-specfic wiring of the CNS ● How do meadow voles and prairie voles differ with regard to pair bonding and care of young? ○ Meadow voles-males do not form lasting relationships (sex then no more interest in female or offspring) ○ Prairie voles-form monogamous relationship and stick around, care for young and act aggressively toward predators; form a pair bond ○ Reproductive success ○ Two types of natural selection ● In addition to its role of regulating water retention in kidneys, antidiuretic hormone (ADH) or vasopressin, also plays an important role in what? ○ Social behavior ○ Critical for partnering and parental behavior ● What’s the deal with expression of the vasopressin receptor gene in the brain of the prairie vole? ○ More highly expressed (both voles have gene, but they’re different) ○ Higher percentage of receptors, increased bonding and care of young, so there is more of it in the prairie voles ● What happened when male prairie voles were treated with a drug that inhibited the brain receptor for vasopressin? ○ Behaved more like the meadow voles ○ Didn’t bond and didn’t stick around ● What happened when researchers inserted the vasopressin receptor gene from prairie voles into male meadow voles? ○ Developed brains with higher levels of the vasopressin receptor ○ Showed many of the same mating behaviors as male prairie voles (pair-bonding) ● What determines which behavioral pattern develops? ○ Although many genes influence pair-bond formation and parenting among voles, the level of the vasopressin receptor alone determines which behavioral pattern develops ● What happened when researchers offered banana slugs to snakes from each wild population? ○ Coastal populations feed on banana slugs, while inland populations feed on frogs and fish ○ Coastal snakes accepted the slugs, but inland did not care for them when given the choice, they refused ● Researchers then collected pregnant snakes from each wild population and houses them in separated cages in the lab. While still very young, the offspring were offered small pieces of banana slug. What were the results? ○ Born from inland mothers were not interested in slugs ○ Born from coastal mothers were interested in slugs ○ Banana slugs appear to be a genetically acquired taste ○ Banana slugs have an odor that attracts coastal snakes ● What were the two groups of birds that Berthold used in their experiment? ○ Group one = offspring of blackcaps captured while wintering in Britain and then bred in Germany in an outdoor cage ○ Group two = consisted of young birds collected from nests near the laboratory and then raised in cages ● What did they do with these birds? ○ In the autumn, Berthold’s team placed the blackcaps captured in Britain and the young birds raised in cages in large, glass-covered funnel cages lined with carbon-coated paper for 1.5–2 hours. ○ When the funnels were placed outside at night, the birds moved around, making marks on the paper that indicated the direction in which they were trying to “migrate” ● What were the results and what did the researchers conclude? ○ The wintering adult birds captured in Britain and their laboratory-raised offspring both attempted to migrate to the west. In contrast, the young birds collected from nests in southern Germany attempted to migrate to the southwest ○ The young of the British blackcaps and the young birds from Germany (the control group) were raised under similar conditions but showed very different migratory orientations ○ migratory orientation has a genetic basis ● What is altruism? ○ A behavior that reduces an animal's fitness, but increases the fitness of other individuals in the population ( belief in or practice of disinterested and selfless concern for the wellbeing of others) ● What is the deal with Belding’s ground squirrel? ○ squirrel that sees a predator approach often gives a high pitched alarm call that alerts unaware individuals to retreat to their burrows. ○ This behavior increases the risk of being killed because it brings attention to the caller’s location ● What’s the deal with workers in honeybee societies? ○ They are sterile and just work for the fertile queen ○ Workers also sting intruders, which defends the hive but they die as a result ● Altruism also observed in naked mole rats. What’s the deal with this species? ○ Each colony has one reproducing queen who mates with 1-3 males (kings) ○ Rest of colony is nonreproductive males and females who forage for roots and tuber and car for the queen, kings, and new offspring ○ Sacrifice their own lives in trying to protect the queen/kings from predators ● How can a Belding’s ground squirrel, a worker honeybee, or a naked mole rat enhance its fitness by aiding members of the population that may be its closest competitors? ○ Increase the population's fitness and success and well being of offspring ● How can altruistic behavior be maintained by evolution if it does not enhance the survival and reproductive success of the self-sacrificing individuals? ○ This increases the fitness of the parents because it maximizes their genetic representation in the population ● Can you see how parents sacrificing for their offspring would work? ○ Maximizes their genetic representation in the population increasing the fitness of the parents ● What about when individuals help others who are not their offspring, especially if they are close relatives? ○ An animal can increase its genetic representation in the next generation by helping close relatives ● What is inclusive fitness? ○ Total effect that an individual has on proliferating its genes by producing its own offspring and by providing aid that enables other close relatives, who share many of those genes, to produce offspring ● What is sociobiology? ○ Certain behavioral characteristics exist because they are expressions of genes that have been perpetuated by natural selection ● What are some of the problems with trying to come up with evolutionary explanations of human behavior? ○ One cannot really say that genes are rigid determinants of behavior ○ Skeptics fear that evolutionary interpretations of human behavior could be used to justify the status quo in human society, thus rationalizing current social injustices ○ Biologists argue that this is a gross oversimplification and misunderstanding of what the data tell us about human biology ○ We should expect inherent variations in behavior as well = NOT robots ○ Perhaps it is our social and cultural institutions that make us distinct and that provide those qualities in which there is the least continuum between humans and other animals Lectures 33,34, and 35: Population Ecology Vocab: Key Concepts/ Main Points: ● Biological processes influence population density, dispersion, and demographics ● The exponential model describes population growth in an idealized, unlimited environment ● The logistic model describes how a population grows more slowly as it nears its carrying capacity ● Life history traits are products of natural selection ● Many factors that regulate population growth are density dependent ● The human population is no longer growing exponentially but is still increasing rapidly ● No organism could produce as many offspring as a semelparous species AND provision them as well as an iteroparous species. There is a trade-off between reproduction and survival. ● Plants and animals whose young are subject to high mortality rates often produce large numbers of relatively small offspring ● In other organisms, extra investment on the part of the parents greatly increases the offspring’s chances of survival ● Statement: Ecologists have attempted to connect differences in favored traits at different population densities with the logistic growth model ● Without some type of negative feedback between population density and the rates of birth and death, a population would never stop growing ● As population density increases, many density-dependent mechanisms slow or stop population growth by decreasing birth rates or increasing death rates ● Populations of large mammals were once thought to remain relatively stable over time, but long-term studies have challenged that idea ● However, when a population becomes crowded and resource competition increases, emigration often increases ● Immigration and emigration are particularly important when a number of local populations are linked, forming a metapopulation ● In a stable regional human population, birth rate equals death rate ● Statement: Population ecologists predict a global population of approximately 8.1-10.6 billion people in 2050 ● Estimating the carrying capacity of Earth for humans is difficult, and estimates have varied widely. But, one thing is clear: At some point, the human population will become too large for the Earth to support unless population growth is controlled ● It has been estimated that the ecological footprint for each person of Earth is 2 hectares (ha). That is an estimate of the aggregate land and water area required by a person for the production of resources consumed and the elimination of wastes generated. A typical ecological footprint for a person in the United States is about 10 ha. ● A typical person in the U.S., Canada, or Norway consumes about 30 times the energy that a person in central Africa consumes. ● Here’s another thing to think about. 80% or more of energy used in developed nations comes from fossil fuels. Questions: ● What is a population? ○ Group of individuals of the same species living in the same general area at a particular time ■ Rely on same resources, influenced by similar enviornmental factors, likely to interact and breed with one another ● How can populations be described by their boundaries and size? ○ boundaries : natural (island) or artificial (county line) ○ Size: the number of individuals in the entire area ● What is population density? ○ number of individuals per unit area or volume ● What is population dispersion? ○ Pattern of spacing; how individuals are distributed within the boundaries ● What are the factors that affect population density? ○ New individuals coming in ■ Births and immigration ○ Individuals going out ■ Death (mortality) and emigration ● Dispersion? ○ pattern of spacing among individuals within the boundaries of the population ● Clumped dispersion? ○ Animals aggregate in patches ○ Plants and fungi clump where soil conditions and other enviornmental factors favor germination and growth ○ where food is abundant, may be associated with mating behavior, effectiveness of predation ○ Ex: Starfish ● Uniform dispersion? ○ evenly spaced, pattern of dispersion may result from direct interactions between individuals in the population ■ Some plants secrete chemicals that inhibit the germination and growth of nearby individuals that could compete for resources ■ Result from antagonistic social interactions such as territoriality - defense of a bounded physical space against encroachment by other individuals ○ maintained by aggressive interactions between neighbors ○ More rare than clumped patterns ○ Ex: Penguins ● Random dispersion? ○ Unpredictable ○ each individual in a population is independent of other individuals ○ Occurs in the absence of strong attractions or repulsions among individuals or where key physical or chemical factors are relatively constant across the study area ○ More rare than clumped ○ Ex: dandelion, think about seeds randomly blowing ● Demography? ○ the study of the vital statistics of populations and how they change over time ○ Interested in birth and death rates ● What is a life table? How is one constructed? What can someone learn from it? ○ Age specific summaries of survival pattern of a population ○ Construct: follow the fate of cohort (a group of individuals of the same age, from birth until all of the individuals are dead) determine the number of individuals that die in each age- group and to calculate the proportion of the cohort surviving from one age class to the next ○ Used to study populations in general, and can predict life expectancy ○ Males have higher death rates than females in Belding’s ground squirrels ● What is a survivorship curve? Explain the survivorship curves shown in the next two slides (Slides 14 + 15) ○ Graphic method of representing data in a life table, plot of proportion or numbers in a cohort still alive at each age ○ a plot of the proportion or numbers in a cohort still alive at each age ○ 14: Survivorship curves for male and female Belding’s ground squirrels. The logarithmic scale on the y-axis allows the number of survivors to be visible across the entire range (2– 1,000 individuals) on the graph ○ 15: Idealized survivorship curves: Types I, II, and III. The y-axis is logarithmic and the x-axis is on a relative scale, so that species with widely varying life spans can be presented together on the same graph ■ Type 1 is flat at the start reflecting low death rates during early and middle life, drops steeply as death rates incrase among older age group (humans) ■ Type 3 drops sharply at the start reflecting high death rates for the young but flattens out as death rates decline for the few that sruvive the early die off: associated with organsism that produce large amounts of offspring and provide little or no care ■ Type 2: intermediate; constant death rate over the organisms life; squirrels and other rodents ● Why do demographers who study sexually reproducing species to determine reproductive rates generally ignore males and concentrate on the females in a population? ○ only females produce offspring ○ view populations in terms of females giving rise to new females ○ simplest way to describe the reproductive pattern of a population is to ask how reproductive output varies with the ages of females ● One part of this type of work is estimating the number of breeding females. The next slide shows how workers are using molecular techniques to study reproductive rates in loggerhead turtles (slide 17) ○ Develop database: using skin sample and PCR genetic profiles are stored in a data base ○ Comparing samples to database: eggshells are collected from nest and use PCR and genetic profiles are determined then compared ● What is a reproductive table? How is one constructed? Tell me about the table in the next slide (slide 19) ○ fertility schedule, is an age specific summary of the reproductive rates in a population ○ constructed by measuring the reproductive output of a cohort from birth until death ○ Tallies the number of female offspring produced by each age-group ○ table : 2 illustrates a reproductive table for Belding’s ground squirrels ■ begin to reproduce at age 1 year, reproductive output rises to a peak at 4 years of age and then falls off in older females ● Change in population size during a dices time interval: ○ Births + immigration - deaths - emigrants = change in population ● When is population growing? ○ When births and immigration is more than deaths and emigrants ● When is population declining? ○ When death and emigrants is more than births and immigrants ● When is there zero population growth ○ When the per capita birth and death rates are equal ○ When they are both the same amounts ● What do you see here (slide 22 and 23) ○ Population growth predicted by the exponential model ○ Higher rate increase = shorter generation species ○ Lower rate of increase = larger generation species ○ Also doubling of population each generation and unlimited space and unlimited resources ● What’s required for exponential growth? ○ Population whose members all have abundant food, free to reproduce at their physiological capacity ● What do you see here (slide 25) ○ it was decimated then it exponentially increased for 60 years ■ This caused them to damage vegetation and put other animals in danger; decimation of food supply was likely ■ Park then relied on birth control and exporting elephants to other countries ● Carrying capacity? ○ maximum population size that a particular environment can sustain ■ Varies over space and time with the abundance of limiting resources ● Logistic growth model? ○ mathematical model to incorporate changes in growth rate as the population size nears the carrying capacity ○ the per capita rate of increase approaches zero as the carrying capacity is reached ● What do you see here (slide 27) ○ Population growth predicted by a logistic model ○ As the rate of population growth decreases as population size (N) approaches the carrying capacity (K) of the environment ○ red line = logistic growth in a population where rmax 1.0 and K 1,500 individuals. (sigmoidal curve) ○ Blue line = population continuing to grow exponentially with the same rmax ● What do you see here (slide 28) ○ Growth in a small culture approximates the logistic growth curve when researcher maintains a constant environment ● What do you see here? (slide 29) ○ Growth in a small laboratory culture does not correspond well to the logistic model (red curve) ○ This pop. overshoots the carrying capacity then it settles down to stable pop. ● How might this model be used in conservation biology? ○ Predicting how rapidly a particular population might increase in numbers after it has been reduced to a small size and for estimating sustainable harvest rates for wildlife populations ○ estimate the critical size below which pop. of organisms may become extinct ■ Used to tell when white rhinoceros may become extinct ● What is life history? ○ Made up of traits that affect an organism’s schedule of reproduction and survival ● What are the three main variables in life history? ○ when reproduction begins ○ how often it reproduces ○ how many offspring are produced per reproductive episode ● What is semelparity? What factors favor this method? ○ “One shot” pattern of big bang reproduction ○ Ex: salmon → mature 1-4 years then comes back and has thousands of eggs ○ Ex: agave “century plant” → grows for years, in an unusually wet year, it send up stalk and seeds, then it dies ● What factors favor the evolution of of semelparity? ○ Where the survival rate of offspring is low, typically in highly variable or unpredictable environments ■ Producing large numbrs of offspring increases probability that at least some of those will survive ● What is iteroparity? What factors favor this method? ○ Repeated reproduction; produce relatively few but large offspring each time they reproduce, provision the offspring better ○ More dependable environments, where adults are more likely to survive to breed again and where competition for resources may be intense ○ Ex: humans and lizards ● Explain this experiment (Slide 37) ○ the effects of parental caregiving in European kestrels for 5 years ○ transferred chicks among nests to produce reduced broods (three or four chicks), normal broods (five or six), and enlarged broods (seven or eight) ○ measured the percentage of male and female parent birds that survived the following winter ○ lower survival rates of kestrels with larger broods indicate that caring for more offspring negatively affects survival of the parents ● What’s the deal with plants that colonize disturbed environments? ○ Produce many small seeds, only a few of which reach a suitable habitat ■ Small size increaes chance of seedling establishment by enabling the seeds to be carried longer distances to a broader range of habitats ○ Plants like dandelions grow quickly and release a large number of tiny fruits, each containing a single seed. Producing numerous seeds ensures that at least some will grow into plants that eventually produce seeds themselves ● What’s the deal with animals that suffer high predation rates? ○ Advantage is to produce a lot of offsprings so some will survive ● Whats up with the brazil nut tree? ○ produce a moderate number of large seeds in pods with nutrients that help the seedlings become established ○ Each seed’s large endosperm provides nutrients for the embryo, an adaptation that helps a relatively large fraction of offspring survive ● Primates? Like money and humans? ○ One or two offspring that they take care of until they can take care of themselves ○ Provisioning and extra care is important in habitats with high population densities ● What is K-selection (= density-dependent selection)? When does K-selection operate? ○ Selection for traits that are sensitive to population density and are favored at high densities ■ Density dependent selection ○ Operate in populations living at a density near the limit imposed by their resources (the carrying capacity, K), where competition among individuals is stronger ○ Ex: Mature trees growing in an old growth forest ● What is r-selection (= density-independent selection)? When does r-selection operate? ○ Maximize reproductive success in uncrowded enviornments (low densitites); ■ density-independent selection ○ Said to maximize r, the per capita rate of increase ○ Operates in environments in which population densities are well below carrying capacity or where individuals face little competition ○ Ex: disturbed habitats = weeds growing in an abandoned agricultural field ● Why does population growth rate decrease as population size approaches carrying capacity? ○ Because there are less survival factors available, so population cannot survive ● What environmental factors keep populations from growing indefinitely? ○ Lack of food, resources, and shelter ● Why are some population fairly stable in size while others are not? ● Some have constant food, resources, and shelter while others do not ● Assuming that immigration and emigration offset one another, when does a population grow? When does a population decline? ○ When death > birth = decline ○ Birth > death = increase ● Death and birth rates that are density independent? ○ A birth rate or death rate that does not change with population density is said to be density independent ● Death and birth rates that are density dependent? ○ Death rate that rises as population density rises is said to be density dependent, as is a birth rate that falls with rising density ● Combination of the two (slide 48) ○ This simple model considers only birth and death rates. (Immigration and emigration rates are assumed to be either zero or equal.) In this example, the birth rate changes with population density, while the death rate is constant. At the equilibrium density (Q), the birth and death rates are equal ○ When population density is low, b>m ■ Population grows until the desnity reaches Q ○ When population density if high, m>b ■ Populatoin shrinks until desnity reaches Q ● What is the deal here? (slide 49) ○ Death rate changes with population density, while birth rate is constant. Both are equal at equolibrium ● What about here? (slide 50) ○ Both are density dependent and at equilibrium they are equal ● Without some type of negative feedback between population density and the rates of birth and death, a population would never stop growing, so how does density dependent regulation provide that feedback? ○ Density-dependent regulation provides that feedback, halting populatoin growth through mechanisms that reduce birth rates or increase death rates ○ Because when there is a high density the rates of growth begin to decrease to lower the density back down (more death and less births) and vice verse ● How is population density being controlled in kelp perch? (slide 52) ○ Kelp perch hiding and kelp bass eat them, more kelp perch (harder to hide), so death rate increases, reach equilibrium ● Tell me about the mechanism = all of which are mechanisms of density dependent regulation ● Competition for resources (slide 54) ○ Increase in density, intensifies competition for resources and nutrients which reduces reproductive rates ○ Farmers minimize the effect of resource competition on the growth of grains such as wheat (Triticum aestivum) and other crops by applying fertilizers to reduce nutrient limitations on crop yield. ● Predation ○ cause of density-dependent mortality if a predator captures more food as the population density of the prey increases. As a prey population builds up, predators may also feed preferentially on that species ● Toxic Wastes: ○ Yeast convert carbohydrates to ethanol in wine making. The ethanol is toxic to yeasts contributing to density-dependent regulation of yeast population. Alcohol content is usually less than 13% because that is the maximum concentratoin of ethanol that yeast can tolerate ○ Within areas, there are a lot of organisms that must get rid of their nitrogen and other wastes, so if you’re in a small area (pond) might have an effect ● Intrinsic Factors: ○ aggressive interactions and hormonal changes that delay sexual maturation and depress the immune system. In this species, high density causes a decrease in the birth rate and an increase in the death rate. ● Territoriality: ○ when space becomes the resource for which individuals compete, limits density ○ Cheetahs use chemical marker in urine to warn other cheetahs of their territorial boundaries ○ Maintainig a territory increaess likelihood that animal will capture enough food to reproduce ○ Presence of suprlus, of nonbreeding, individuals is a good indication that territoriality is restricting population growth ● Disease: ○ Respiratory diseases spread through the air striking a greater percentage of people in densely populated cities ○ Increases mortality among the race ● What is population dynamics? ○ population fluctuations from year to year or place to place; influenced by many factors affecting other spcies ○ Focuses on complex interactions between biotica and abiotic factors ● Wht is up with the moose population Isle Royale in Lake Superior ○ Fluctuation in population even when there was no fluctuation in immigration/ emigration because lake not frozen, but still changed because wolf predation at peak and harsh winter weather increasing the energy needs of the moose and made it harder for the moose to find food under the deep snow ● Population cycles in the snowshoe hare and lynx? ○ Hare numbers rise and fall in approximately a 10 year cycle ○ Hypotheses: ■ 1. cycles may be caused by food shortage during winter (not as important) ■ 2. cycles may be due to predator-prey interactions ■ 3. vary with sunspot activity, which also undergoes cyclic changes ○ availability of prey is the major factor influencing population changes for predators ○ Long-term experimental studies help to unravel the causes of such population cycles ● Whats a metapopulation? Why are immigration and emigration important for maintaining a metapopulation? ○ when a number of local populations are linked ○ Immigration and emigration link the Belding’s ground squirrel population we discussed earlier to other populations of the species, all of which make up a metapopulation ○ Patches with many individuals can supply more emigrants to other patches ○ If one patch becomes extinct, patch it occupied can be recolonized by immigrants from another populatoin ● What’s the deal with the areas actually occupied by this butterfly and the total areas that could be occupied? ○ Individuals can move between local populations and colonize unoccupied patches ○ 500 occupied out of 4000 suitable patches ○ New populatoins appear and existing ones become extinct constantly shifting the locations ● What does it mean to say that this species persists in a balance of extinctions and re- colonizations? ○ New populations of the butterfly regularly appear and existing populations become extinct, constantly shifting the locations of the 500 colonized patches ● What do you see here? (slide 70) ○ global human population has grown almost continuously throughout history, ○ It skyrocketed after the Industrial Revolution ○ rate of population growth has slowed in recent decades, mainly as a result of decreased birth rates throughout the world ● What has happened to the growth rate since the 1960s? What does the reduction in growth rate indicate? Why as the growth rate slowed down? ○ Decreased ○ That it will continue to decrease / slow down ○ Departed from true exponential growth ○ Result of fundamnetal changes in population dynamics due to diseases (AIDS) and voluntary populatoin control ○ the sharp dip in the 1960s is due mainly to a famine in China in which about 60 million people died ● What are the two extreme ways to have zero population growth? ○ 0 population growth = High birth rate - High death rate ○ 0 population growth Low birth rate - Low death rate ● What is demographic transition? What contributes to demographic transition? ○ movement from high birth and death rates toward low birth and death rates ○ contributes : accompany industrialization and improved living conditions ○ Associated with increase in quality of health care and sanitation as well as improved access to education, especially for women ○ Reduced family size is the key ● If populations are near equilibrium in industrialized nations and even below replacement in many, why is the human population still growing? ○ Due to less industrialized countries that do not have access to family planning and contraception where about 80% of the world’s people now live ● What do these different age-structure pyramids indicate about the populations of these countries? How can they help us make predictions about the future with regard to both population growth and social conditions? ○ Afghanistan: lot of young people, die young, growth of 2.6% = rapid growth ○ US: most in youth, teens, and middle aged adults, 1.0% growth = slow; baby boom after WWII; US pop still growing because boomers and boomers offspring are at reproductive age; populatoin also growing because of immigration; slow growth ○ Italy: low youth, high young-middle aged adults, old like youth = 0 % growth; ○ Look at the trends and how people will be cared for (healthcare) enough youth to care for old, lower pop. growth usually more socially stable the nation ● How is infant mortality figured? How is life expectancy figured? ○ # deaths per 1,000 live births ○ predicted average length of life at birth ● What do you see here (slide 78) ○ Infant mortality versus life expectancy ○ Low infant mortality in industrialized countries, high in non industrialized ○ High life expectancy in industrialized, medium in non industrialized ● How many humans can our biosphere support? ○ 10–15 billion ● Will the world be overpopulated in 2050 if predicted is 8.1 to 10.6 billion? Is the world already overpopulated? ○ there is no single carrying capacity for the human population on Earth. How many people our planet can sustain depends on the quality of life each of us enjoys and the distribution of wealth across people and nations ● What do we mean by ecological footprint? How can it be estimated? ○ aggregate land and water area required by each person, city, or nation to produce all the resources it consumes and to absorb all the waste it generates ○ add up all the ecologically productive land on the planet and divide by the population ○ Typically in US is 10 ● Is this sustainable? What are the consequences? ○ this unsustainable reliance on fossil fuels is changing Earth’s climate and increasing the amount of waste that each of us produces. Ultimately, the combination of resource use per person and population density determines our global ecological footprint ● So, we can only speculate about Earth’s carrying capacity for the human population and about what factors will eventually limit our growth. What are some of those limiting factors? How long do you think we can wait to take action? ○ Perhaps running out of food, space, or non renewable resources could limit ○ Act now, as no population can continue to grow indefinitely ○ No single carrying capacity for the human population on Earth, too many factors like comfortability and wealth to account for ○ we can decide whether zero population growth will be attained through social changes based on human choices or, instead, through increased mortality due to resource limitation, plagues, war, and environmental degradation ○ Technology has increased the carrying capacity but no population can grow indefinitely Lectures 36 and 37: Community Ecology Vocab: ● Key Concepts/ Main Points: ● Community interactions are classified by whether they help, harm, or have no effect on the species involved. ● Diversity and trophic structure characterize biological communities. ● Disturbance influences species diversity and composition. ● Similar species can coexist in a community if one or more significant differences in their niches arise through time. Evolution by natural selection can result in one of the species using a different set of resources ● Two species cannot coexist permanently in a community if their niches are identical ● Species can partition their niches not just in space, as lizards and barnacles, but in time as well ● An early view of community structure envisioned mature communities as being at an equilibrium and being more or less stable over time unless seriously disturbed. This was known as a climax community ● Later views envisioned communities as either integrated units or assemblages of species that are found together simply because they happen to have similar abiotic requirements Questions: ● What is biological community? ○ A group of populations of different species living close enough to interact ● Interspecific Interactions? ○ key relationships in the life of an organism are its interactions with individuals of other species in the community ■ Competition, predation, herbivory, symbiosis (including parasitism, mutualism, commensalism), and facilitation ● Interspecific competition? What kind of interaction is it? ○ is a -/- interaction that occurs when individuals of different species compete for a resource that limits their growth and survival ● What is competitive exclusion? ○ And outcome when there is a light reproductive advantage that eventually leads to local elimination of the inferior competitor ○ Two different bacterias thrive on their own but when both in the same culture, one wins out ● What is ecological niche? What does it mean to say that two species cannot coexist permanently in a community if their niches are identical? ○ The sum of a species’ use of the biotic and abiotic resources in its environment; habitat is the “address” and niche is the “profession”; ecological role of how it fits into an ecosystem ○ Eventually one of the will have to leave or will be lead to their demise via competitive exclusion ● What is resource partitioning? ○ The differentiation of niches that enables similar species to coexist in a community ● Fundamental niche? What is realized niche? ○ The niche potentially occupied by that species ○ The portion of its fundamental niche that it actually occupies in a particular environment ● Barnacles experiment? (slide 20) What do you think would happen if Chthamalus rather than Balanus was removed? Why? ○ two barnacle species— Chthamalus stellatus and Balanus balanoides—that have a stratified distribution on rocks along the coast of Scotland ○ Chthamalus is usually found higher on the rocks than Balanus ○ To determine whether the distribution of Chthamalus is the result of interspecific competition with Balanus, Connell removed Balanus from the rocks at several sites ○ Chthamalus spread into the region formerly occupied by Balanus ○ Interspecific competition makes the realized niche of Chthamalus much smaller than its fundamental niche ○ Balanus would have done the same exact thing if Chthamalus was removed ● Deal with common spiny mouse and the golden spiny mouse? ○ Patition niches in not only space, but time as well ○ Common spiny mouse is nocturnal ○ Golden spiny mouse is diurnal, but is naturally nocturnal so it has to override its biological clock in the presence of the common spiny mouse ○ When the common was removed then the golden went back to nocturnal ○ So, interspecific competition exists between the two and partitioning the time of when they are active allows them to coexist ● Character displacement? Deal with the finches (side 27)? ○ characteristics to diverge more in sympatric than in allopatric populations of two species ○ Allopatric populations of Geospiza fuliginosa and Geospiza fortis on Los Hermanos and Daphne Islands have similar beak morphologies (top two graphs) and presumably eat similarly sized seeds. However, where the two species are sympatric on Santa María and San Cristóbal, G. fuliginosa has a shallower, smaller beak and G. fortis a deeper, larger one (bottom graph), adaptations that favor eating different-sized seeds ● What is predation, and what kind of interaction is it? ○ positive /negative (+/-) interaction between species in which one species, the predator, kills and eats the other, the prey ● What sorts of adaptations do predators have? ○ Acute senses to find prey ○ Claw teeth, fangs, stingers, or poison ○ Heat sensing organs in rattlesnakes and vipers and then kill by injecting with fangs ○ Fast and angile ● Explain the adaptations of prey in the following slides ● Porcupine (slide 33) ○ Mechanical defense, have needles ● Skunk (slide 34) ○ Chemical defense, spray that smells ● Poison dart frog (slide 35) ○ Aposematic coloration, warning coloration that is a bright chemical defense; predators avoid prey that have bright color patterns ● Canyon tree frog (slide 36) ○ Cryptic coloration, camouflage to avoid detection from predators ● Nonvenomous hawkmoth larva (slide 37 and 38) ○ Batesian mimicry, a palatable or harmless species mimics an unpalatable or harmful one ○ Puffs up its head and thorax when disturbed, looking like the head of a small poisonous snake and it mimics behavior as it weaves its head back and forth and hisses like a snake. ○ Viceroy butterfly and monarch ● Cuckoo bee and yellow jacket (slide 39) ○ Müllerian mimicry, two or more unpalatable species resemble one another ○ The more unpalatable prey there are, the more quickly predators learn to avoid prey with that particular appearance ○ convergent evolution, unpalatable animals in several different taxa have similar patterns of coloration: Black and yellow or red stripes characterize unpalatable animals as diverse as yellow jackets and coral snakes ○ Frogs also do Müllerian mimicry ● As a predator what do the following slides show about how the mimic octopus uses mimicry? (slides 43-45) ○ Mimicks a sea snake, flounder, and stingray to scare prey or disguise itself from the prey then it attacks ● Herbivory? And what kind of interaction is it? ○ A positive/negative interaction in which an organism eats parts of a plant or alga ● What sort of adaptations do they have? ○ Chemical sensors on feet or sense of smell to tell if plant is toxic or only eat certain parts of the plant (like on a flower with a bee) ○ Specialized teeth or digestive system ● Plant adaptations to protect against herbivores? ○ Chemical toxins ○ Spines and thorns ○ Chemicals that cause abnormal development in some insects ● Symbiosis? ○ When individuals of two or more species live in direct and intimate contact with one another, their relationship ○ includes all such interactions, whether they are harmful, helpful, or neutral ○ Some define symbiosis more narrowly as a synonym for mutalism, an interaction in which both species benefit ● Parasitism? Interaction type? What is an endoparasite? What is an ectoparasite? ○ A positive/negative symbiotic interaction in which one organism, the parasite, derives its nourishment from another organism, its host, which is harmed in the process ○ Parasites that live within the body of their host, such as tapeworms, are called endoparasites ○ Parasites that feed on the external surface of a host, such as ticks and lice are called ectoparasites ● What is mutualism and what kind of interaction is it? What is obligate mutualism? What is facultative mutualism? ○ is an interspecific interaction that benefits both species (+/+) ○ Obligate: one species has lost the ability to survive without its partner ■ Termies and the microorganisms in their digestive system ○ Faculative: both species can survive alone ■ Certain species of acacia trees have hollow thorns that house stinging ants which feed on nectar produced by the tree and on protein-rich swellings at the tip of leaflets ■ Acacia benefits because the ants attack anything that touche the tree removing fungal spores, small herbivores, and debris; also clip vegettion that grows close to the acacia; they can get along without eachother ● Commensalism? Interaction type? ○ Interaction between species that benefits one of the species but neither harms nor helps the other ○ A(+/0) interaction ○ Cowbirds and cattle egrets feed on insects flushed out of the grass by grazing bison; birds benefit as they increase their feeding rates ○ The bison benefit a little as the birds remove ticks and could warn of a predators approach ● Facilitation? Interaction type? ○ Species can have positive effects (+/+ or 0/+) on the survival and reproduction of other species without necessarily living in the direct and intimate contact of a symbiosis ○ Species richness increases in presence of juncus ● What is
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