BIOL 3440 Quiz: Test 3 Study Guide

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BIOL 3440
Matthew S.Grober 

Test 3 Study Guide – Fundamentals of Evolution I. Chapter 12: The Evolution of Social Behavior a. Female house mice i. Aggressively defend their pups against same-species intruders ii. Counted seconds lactating mothers spend attacking intruding males during 3-min trials; found that some females defend their pups more aggressively than others iii. Resemblance between mothers and daughters- 60% variation among females was due to differences in genes iv. Assigned mice to a control and selected line • Each generation chose females at random from control and kept offspring as breeders • Selected line, kept the offspring with the most aggressive female in each family; by 8 generation females were defending pups more vigorously than in the control line • Selected mice showed altered expression of a number of genes b. Social behavior evolves by the same mechanisms as other traits A. 12.1: Four kinds of social behavior a. Simplest social interaction involves 2 individuals: actor and recipient i. Actor does something for the recipient, the outcome may be good or bad for either or both ii. Good outcome increases direct fitness and bad decreases direct fitness b. Mutually beneficial- both the actor and recipient enjoy increased reproductive success c. Selfish- actor benefits at the expense of the recipient d. Altruistic- actor makes a sacrifice on behalf of the recipient e. Spiteful- the actor suffers a loss in order to impose a penalty on the recipient 1. Mutual benefit a. Cuckoo i. Adult males and females form mated pairs but pairs nest alone • Genetically unrelated couples nest together ii. All females lay eggs and all adults work together to incubate the eggs, feed the chicks, and defend the nest iii. Drive away predators by mobbing iv. Why mated pairs join forces instead of building own nest? • Only 2 pairs that tried to nest alone o Both cases, all eggs were taken by predators • 2 pair coalitions more successful at defending nests and 3 pair even more successful o Regardless of which female laid their egg first, each had roughly equal reproductive success v. Before each female lays her egg, will toss out eggs already laid vi. Communal breeding • Explanation why mated pairs join coalitions • Each pair achieves higher reproductive success by working together • Fitness benefit to the actor offers explanation of evolution of mutual benefit • Frequent presence of conflict has the risk of cheaters 2. Selfishness a. Cane toad tadpoles i. Tadpoles routinely eat cane toad eggs ii. Wanted to know if were merely generalist consumers that eat eggs as they come across them or targeted cannibals that actively seek cane toad eggs • Funnel traps that lure at random using cane toad eggs as bait • Other trap left empty as a control • 14 native in control versus 12 in baited traps o Native frog tadpoles are not attracted to cane toad eggs • Cane toad tadpoles are attracted to cane toad eggs late in development o Chemical cues released are bufogenins that make to deter heterospecific predators o Also baited with bufogenins, trapped most tadpoles • Concluded are targeted cannibals iii. Why cannibalism? • Tadpoles can complete development and metamorphose into toads on a diet consisting of cannibalized eggs • Reduction in population density that results from cannibalism enables tadpoles to grow faster, metamorphose more quickly, and survive at higher rates iv. Provides 2 benefits: nutrition and reduction of competition b. Selfish tadpoles achieve higher fitness than unselfish ones 3. Altruism a. Belding’s ground squirrels i. Live in groups in the mountains ii. When a squirrel notices that is group is being stalked by a predator, sometimes gives a loud call, alarm calls iii. 2 kinds of alarms: trill in response to mammals approaching on foot and whistle to hawks attacking on the wing • Whistling squirrel is captured only 2% of the time while non- whistling squirrels are captured 28% of the time o Squirrel raising the alarm reduces its own chances of dying by informing the hawk that the caller has seen it, and the caller brings panic and confusion to the other squirrels o Whistles are selfish • Trilling squirrel is killed 9% of the time while non-trilling squirrel are killed 4% of the time o Squirrel raising the alarm increases its own peril to benefit others o Trills are altruistic 4. Spite a. Bacteria i. Bacteria make bacteriocins that are lethal to other members of the same species ii. Makers are either immune or lack poison’s molecular target or resistance because they make an antidote iii. Many strands that make bacteriocins release the toxins by rupturing their cell walls and spilling the contents to the outside • Reduces direct fitness o Because bacteriocins require energy and materials to make strains grow slower than identical strains that do not produce the toxin o By making and releasing bacteriocins o Weapons are lethal, a bacterial cell that constructs and deploys them reduces the direct fitness of susceptible cells iv. Whether spiteful interactions occur in nature? • Isolated 36 strains • 1,260 pairwise combinations where one bacterial strain served as actor and a different strain served as recipient • No strain inhibited any other strain from its own soil sample and every strain from each sample inhibited all the strains from the other sample • Do behave spitefully in nature B. 12.2: Kin selection and costly behavior a. Selection could favor traits that result in decreased direct fitness if they increase the survival and reproductive success of close relatives 1. Inclusive fitness a. William D. Hamilton i. Genetic model showing how an allele causing altruistic behavior can spread ii. Behavior of an individual toward others can influence the success of the actor’s genes iii. Relatedness- r, relatedness of the actor and recipient; measure of genetic similarity between individuals iv. Hamilton’s rule: altruism will increase in frequency • Br – C > 0 • B- benefit to the recipient • C- cost to the actor • B and C measured in units of surviving offspring • Altruism is more likely to spread when benefits to the recipient are great, the cost to the actor is low, and the participants are closely related b. John Maynard Smith i. Rare dominant allele A in birds that always lay 2 eggs • Because allele is rare, nearly all copies are in heterozygotes ii. A’s only influence on phenotype, relative to a, is that when it finds itself in an older sibling • A causes carrier to beg less aggressively for food • Diminishes older sibling’s prospects, reducing the number of eggs it can expect to produce over its lifetime by C o Because ½ the eggs lost would have carried the copy of A, the altruistic behavior reduces the number of copies transmitted by C/2 • Younger sibling is better fed, increases the number of eggs it can expect to produce over its lifetime by B o Increases the number of A transmitted by Bp/2 o p is the probability that A occurs in the younger sibling o Net gain of A in copies transmitted if Bp > C iii. To estimate p, it will occur in the younger sibling (A is rare) only if one or the other of the younger sibling’s gene copies is identical by descent to the copy of A in the older sibling • The probability that a gene copy sampled from 1 individual is identical by descent to a gene copy present in another individual is a commonly used definition of relatedness iv. Conditions for A to increase is Br > C • If birds are monogamous so that the chicks in the clutch are always full sibs, r is ½ • Older chick will value the survival and reproduction of its sibling at half the worth of its own • If are half-sibs, r is ¼ • Older chick will value the fitness of its siblings at a quarter the worth of its own v. General deviations of Hamilton’s rule • Assumptions about the number, the frequency, and dominance of the genes involved • Essence of all derivations is the inclusion of 2 components of an individual’s genetic contribution to future generations c. Direct fitness- results from reproduction an individual achieves on its own, without help from related individuals d. Indirect fitness- results from additional reproduction by relatives that is made possible by the individual’s actions e. Inclusive fitness- the sum of its direct and indirect fitness f. Kin selection- natural selection leading to the spread of alleles that increase the indirect component of fitness 2. Alarm calling in black-tailed prairie dogs a. Power of kin selection in explaining the evolution of altruism b. Characteristics of prairie dogs i. Large squirrels ii. Live in family groups called coteries iii. Each coterie holds a territory within a prairie dog town iv. Females typically remain in their birth coterie for life whereas males disperse at maturity v. Prey to badgers, bobcats, coyotes, eagles, and falcons vi. Spend half of the aboveground time standing watch vii.Spies a predator sounds an alarm c. Unable to document for certain whether selfish or altruistic i. Suspected altruistic d. Is calling behavior a result of kin selection? i. Simulated predator attacks ii. Both male and female are more likely to give alarm calls if their coterie includes genetic kin iii. Individuals give calls nearly as often when the kin they live with are siblings as when they are offspring iv. Altruistic alarm calls are not dispensed randomly, they are nepostistic • Self-sacrifice is directed at close relatives and thus should result in indirect fitness 3. Measuring costs and benefits for adoptive mother squirrels a. Red squirrels i. Each squirrel defends a feeding territory that, except when mothers are caring for kittens, it occupies alone ii. Spring and summer, researchers livetrap and tag squirrels to monitor reproduction of females and track the growth and survival of their litters iii. Includes 34 orphaned litters • Could have been adopted and nursed by females nearby • 7 litters, genetic relative was among adoptive mothers • 27 litter, no relatives as adoptive mothers iv. Direct fitness cost to a potential adoptive mother of adding a kitten to her litter • Adding a kitten reduces the chances that each of her existing offspring will survive, so the mother’s direct fitness increases with her original litter size v. 5 cases where mothers adopted, the indirect benefit was above the break- even point vi. 2 cases the benefit was below the breakeven point 4. Kin selection and human behavior a. Kin selected and inherited wealth i. Humans care what happens to our wealth when we die because we want the resources we have accumulated to keep working on our genes’ behalf ii. First prediction: people will leave a greater share to kin than to non-kin iii. Concluded that the data are in broad accord with kin selection theory • Suggests that natural selection among our ancestors left us with a tendency to feel more generous to more closely related kins b. Kin selection and trust i. Bargaining game- trusting always gave player 1 a chance to get more money at the risk of getting less, being selfish always gave player 2 the biggest reward and not being trusted the smallest ii. P1- volunteers were more trusting toward opponents who looked like kin iii. P2- volunteers were no less selfish to opponents who looked like kin than to opponents who did not iv. If opponent is anything less than a full sibling, being selfish offers a higher payout v. Both more trusting as P1 and more selfish as P2 c. Cooperative breeding in birds i. Hamilton’s rule can help us understand the behavior of individuals within species ii. Cooperative breeding- illuminate patterns of behavior among species • Bird families, young that are old enough to breed on their own instead remain and help their parents with their siblings iii. Whether kin selection helps explain evolutionary transitions from noncooperative breeding to cooperative breeding and vise versa • Focused on relatedness • Higher relatedness among siblings in a family should facilitate the evolution of helping at the nest, and lower relatedness should facilitate the loss of helping • Hypothesized that relatedness has influence on evolutionary trends o Low levels of female promiscuity facilitate the evolution of cooperative breeding o Investments older offspring make in helping their parents breed yield greater gains in indirect fitness 5. Greenbeard alleles a. Altruistic behavior have risen to high frequency by playing the odds b. Alleles for altruism induce the carriers to obey Habilton’s rule (helping kin only when the product of benefit and relatedness is sufficiently high and the cost is sufficiently low)- alleles win more often than they lose c. Greenbeard effect i. Drive an allele for altruism to high frequency ii. Allele that simultaneously causes its carriers to grow green beards, to recognize green beards on others, and to behave altruistically toward them • Carriers would not have to distinguish full siblings versus half- siblings versus cousins and adjust their behavior accordingly • Alleles for altruism would not have to play the odds • Sure winner iii. Slime mold • Mass that travels • Wild type allele csA o Exhibits all the properties of a greenbread allele o Protein encoded by csA sits on surface of slime mold and sticks to other copies of itself on the surface of other cells o Specifies a trait and ability to recognize the trait in others • Mixed wild with slime mold carrying a knock out allele of the csA gene o Wild type cells were disproportionately represented in the stalks o Wild type ended up on the bottom, relegated to a supporting and nonreproductive role because stuck to each other more strongly o Wild type allele appears to not be a greenbeard but opposite; altruist that sacrifices itself for the beardless ▪ It should quickly disappear in lab culture o Mixed cultures in natural environment ▪ More difficult for amoebae to stream together in soil ▪ Wild type stick to each other and pull each other ▪ Wild type cells disproportionately represented among the spores in fruiting bodies as well as in the stalks ▪ Knock out cells are less adhesive and tend to get left out o Natural conditions, wild type allele of csA renders its carriers preferentially altruistic toward other wild type cells • Kin selection also works at the level of individual alleles 6. Kin selection and spite i. Spiteful interaction, the benefit to the recipient is actually a cost a. Negative relatedness i. The definition of relatedness geometrically • Actor is a homozygote for an allele that is fairly low frequency • Recipient 1 is a heterozygotes and recipient 2 is a homozygote for the other allele • Relatedness between actor and a recipient is the distance from the frequency in the population to the frequency in the recipient’s genotype as a fraction of the distance from the frequency in the population to the frequency in Actor • Actor and recipient 1 have positive relatedness o 1 is more genetically similar to actor than is the average individual o 1 reproduces, it increases the frequency of actor’s allele in population ▪ If actor helps 1 reproduce it contributes to actor’s inclusive fitness • Actor and recipient 2 have negative relatedness o Sits on the opposite side of the population frequency from actor o Actor impedes 2 from reproducing to contribute to actor’s inclusive fitness ii. Recipient 1, 2, and actor on how spite can evolve b. The enemy of my enemy is my friend i. Individuals with positive relatedness to the actor indirectly benefit when the actor pays a cost to reduce the fitness of competitors with negative relatedness to the actor ii. Xenorhabdus bovienii • Pathogen of insects • Isolated 2 strands rd o Spiteful- makes bacteriocins that kill a 3 strain, the susceptible competitor o Benign- does not o Neither the spiteful nor benign can kill a strain of X. koppenhoeferi (resistant competitor) o Neither the susceptible competitor nor the resistant competitor makes bacteriocins of its own • 2 controls o Inoculated spiteful and benign strains by themselves into caterpillars and monitored bacterial growth rates; no significant growth o Inoculated spiteful and benign strain into caterpillars along with the resistant competitor; benign grew significantly faster than spiteful strain • Caterpillars inoculated with a mixture of competitors and spiteful strain survived longer • Caterpillars inoculated with a mixture of competitor and benighn strain died just as fast • Spiteful interactions can alter course of infection C. 12.3: Multilevel selection and cooperation a. Cooperation- beneficial or costly to the actor, beneficial to the recipient, and selected for at least in part because the recipient benefits i. Encompasses all cases of altruism and some cases of mutual benefit b. David Sloan Wilson- model showing that cooperators can increase in overall frequency when the higher productivity of groups with many cooperators outweighs the lower relative fitness of cooperators within groups 1. A numerical example of multilevel selection a. 2 types of individuals: cooperative and selfish at frequencies of 0.5 i. Reproduce by cloning ii. Before reproducing form groups of 3 at random iii. Reproduction within groups iv. How frequency cooperators change across generations? • Success depends on its own behavior and that of its group mates • Cooperator always increases the reproductive success of everyone in its group, but can be exploited to additional advantage by selfish individuals o Within mixed groups the frequency of cooperators falls from one generation to the next b. Simpson’s paradox- pattern of contrasting trends within groups versus a population; if cooperators provide sufficient benefit to their social groups, cooperation may increase in frequency in the population at large, even if it decreases in frequency within groups c. Models of multilevel selection i. Selfish individuals have higher fitness than cooperators ii. Groups with more cooperators produce more offspring iii. Can be any size and composed of kin 2. Multilevel selection and cooperation in bacteria a. Genetically engineered strains of E. coli to be selfish or cooperative i. Cooperative make and release the antidote to a poison ii. Selfish make no product, but are genetically identical b. Bacteria grown in the absence of poison, the selfish bacteria grow faster because not making product c. Each strand is grown separately in the presence of poison cooperative bacteria grow faster d. What happens when the 2 strains are grown together in the presence of the poison? i. Selfish pick up the antidote released by cooperators escape the effects without paying the cost of production ii. The higher the proportion of cooperators in any given culture, the faster the culture grew (cooperators provide a common good to their social groups iii. The frequency of cooperators fell (selfish benefitted from the common good without paying the price) iv. Combined and mixed cultures in each replicate found that the global frequency of cooperators always rose (selection against cooperators within cultures was outweighed by selection among cultures favoring cooperators 3. Multilevel selection in a plant a. Thale cress i. Selection for increased leaf area at the level of groups • Each generation, picked 3 groups with the highest mean leaf area to serve as breeders • Each selected breeding group produced the seeds that served as founders for the next generation ii. Group level selection for reduced leave area iii. Most dramatic in the absence of individual selection iv. Selection at the level of individuals within groups interfered with this response v. Interference competition- when individuals that interfere with their neighbors are present in a group, the entire group may suffer 4. Multilevel selection and human morality a. Human moral sense evolved in the context of multilevel selection b. Measured cooperatively by asking individuals to play a public goods game i. Gave each subject honey sticks and offered them the option of anonymously donating as many as they wished to the public good ii. Each stick donated, researchers donated 3 iii. After all made donations, researcher would divide pool evenly among members iv. Bigger donations more cooperative v. More variation among bands and less variation within bands vi. Genetically related individuals tended to resemble each other in cooperativity B. 12.4: Cooperation and conflict 1. Parent-offspring conflict a. Conflict over provisioning of offspring i. Weaning conflict • Aggressive and avoidance behaviors common toward the end of nursing • Mothers ignore or push young away trying to nurse and offspring scream or attack mothers ii. Feeding chicks • Increases possibility that chicks will survive but costs of care expended on 1 offspring is care that cannot be expended on others • Carrying for present offspring may reduce the number of offspring a parent will be able to produce in the future • Eventually benefits level off • Once probability is high parental investments do not raise it further iii. Chicks should beg more vigorously when their nestmates are less closely related b. Harassment in white-fronted bee-eaters i. Fathers occasionally coerce sons into helping to raise their siblings; harassing sons who are trying to raise their own ii. Harassment behavior is not targeted randomly but is preferentially directed at close kin iii. Instigators are actively trying to break up the nesting attempts of close kin and suggest that instigators do this to recruit the targeted individuals as helpers at their own nest iv. Why sons do not resist harassment more effectively? • Harassment can be successful because sons are equally related to their own offspring and to their siblings • Parents are motivated to harass because they are more closely related to their own offspring than they are to their grandchildren • Parents at a nest unaided by relative are able to raise ½ offspring o First time breeder the fitness payoff from finding a mate and breeding without helpers is only slightly greater than the fitness payoff from helping c. Siblicide i. Young siblings to kill each other while parents look on passively ii. Short term food shortages older chicks eat less helping other sib survive; famine continues older chick attacks and kills the younger iii. Reduces competition to raise odds of surviving iv. Different species: parents are more likely to intervene or prevent death 2. Cooperation and conflict among non-kin a. Reciprocity i. The exchange of favors that ultimately benefit both participants ii. Doing favor for another individual may be costly in the short term, but if recipient eventually pays it back with a favor of greater value, the actor comes out ahead in the long run iii. Unrelated baboons • Offer grooming and providing support in aggressive encounters with a 3 baboon iv. While mutually beneficial in the long run, it leaves the individual who acts first vulnerable to a net loss in the short run • Can happen if recipient cheats by failing to return the favor • Can avoid being taken advantage of is to punish cheaters v. Reciprocity is most likely to evolve when the same individuals repeatedly interact with each other, have many opportunities to exchange favors, sometimes need and sometimes can off favors, and have good memories b. Reciprocity and punishment in humans i. Moralistic aggression, gratitude, guilt, and trust are adaptations that evolved in response to selection for reciprocity ii. Punishment not an option the mean donation started at an intermediate level and fell as players reacted to being taken advantage of iii. Punishment allowed the mean donation started at and intermediate level and rose as players paid to fine each other C. 12.5: The evolution of eusociality a. Eusocial- describe animals that have overlapping adult generations in which nonreproductive individuals participate in the cooperative care of young 1. The haplodiploidy hypothesis a. Unusual form of sex determination i. Males haploid ii. Females diploid b. Haplodiploidy- more closely related to their sisters than their own offspring i. Sisters share all genes inherited from father and mother; to be identical is ¾ probability ii. To own offspring have usual relatedness of ½; can maximize their inclusive fitness by acting as workers and investing in the production of sisters rather than by acting as reproductives iii. Been abandoned; not necessary for evolution of eusociality 2. The monogamy hypothesis a. Lifelong monogamy facilitates the evolution of eusociality? i. When an individual can be certain that future siblings will be full siblings, a new brother or sister increases an individual’s inclusive fitness just as much as an offspring does ii. Not sufficient for the evolution of eusociality 3. The ecology and life-history hypothesis a. A scenario for evolution of eusociality in vespid wasps i. Females have a choice to nest on their own or in copperation with others ii. Females that begin reproductive careers as helpers eventually become breeders; can switch roles iii. Some committed to 1 role in life II. Chapter 13: Aging and Other Life-History Characters 1. Blue footed booby a. Attract mates by showing foot color b. Dull blue to bright green c. Females are more attracted to green i. Color of feet can change depending on how healthy they are d. Maintaining enough pigment gets harder with age i. Males that take a year off for reproduction have brighter feet for their age ii. Conflict between reproductive investment this year versus future years • Best compromise = highest lifetime reproductive success 2. Reproduction a. Some mature early and reproduce quickly and others mature late and reproduce slowly b. Plants have a range of reproductive life spans c. Some produce enormous numbers of tiny eggs while others produce small numbers of large eggs 3. Life history analysis- the branch of evolutionary biology that attempts to make sense of the diversity in reproductive strategies 4. Trade-offs a. The amount of energy an organism can harvest is finite, and biological processes take time b. Energy and time devoted to one activity are energy and time that cannot be devoted to another c. Whenever there is a trade-off between different components of fitness, we expect natural selection to favor individuals that allocate energy and time with an optimal balance between benefits and costs, thereby maximizing lifetime reproductive success i. Environmental variation is the source of much of the life history variation A. 13.1: Basic issues in life-history analysis 1. Opossum a. Where they get their energy at different stages of life and functions to where it is allocated b. 2 scenarios i. Stop allocating energy to growth at an earlier age and reach sexual maturity more quickly; trade off- produce smaller litters ii. After reaching sexual maturity allocate less energy to reproduction and more repair; trade off- allocating less energy to reproduction means having smaller litters 2. Differences in life histories concern differences in allocation of energy 3. Sand crickets a. Females: short or long winged i. Short winged devoted a larger share to reproduction ii. Long winged devoted a larger share to flight iii. Due to differences in genes b. Manage at least this aspect of trade off between flight capacity and reproduction by means in genetic regulation c. Long winged exposed to methoprene i. Induced to develop short winged d. Ability to fly comes with a fitness cost: receive less energy the ovaries of long winged grow more slowly and have lower early life fecundity i. Long wing can break down their flight muscles to shift to short to reproduce B. 13.2: Why do organisms age and die? a. Senescence- late life decline in an individual’s fertility and probability of survival; aging b. Aging should be opposed by natural selection c. Theories of why aging exists i. Rate of living theory- invokes an evolutionary constraint; posits that population lack the genetic variation to respond any further to selection against aging ii. Evolutionary theory- invokes a trade-off between the allocation of energy to reproduce versus repair 1. The rate-of-living theory of aging i. Aging is caused by the accumulation of irreparable damage to cells and tissues ii. Damage to cells and tissues is caused by errors during replication, transcription, and translation, and by the accumulation of poisonous metabolic by-products iii. Rate-of-living theory- all organisms have been selected to resist and repair cell and tissue damage to the maximum extent physiologically possible • Populations lack the genetic variation that would enable them to evolve more effective repair mechanisms than they already have • 2 predictions o Because cell and tissue damage is caused in part by the by-products of metabolism, aging rate should be correlated with metabolic rate o Because organisms have been selected to resist and repair damage to the maximum extent possible, species should not be able to evolve longer life spans, whether subjected to natural or artificial selection a. Tests of the rate-of-living theory i. Aging will correlate with metabolic rate, with comparative study of mammals • All should expand about the same amount
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