Short-Answer Please read the question carefully and supply the requested information in the space provided. Please answer 10 of the 14 questions.

1. Explain why Bateman argues that males tend to be more sexually aggressive than females? Give an example in which females are more sexually aggressive and explain why.

Males make many small gametes and females make scarcer large gametes. Males must compete for access to scarce gametes controlled by females and, and unlike females, their reproduction is proportional to their number of mates. The need to compete and their dependence on numbers of matings for determining their reproductive success places special importance on being sexually aggressive for males.

2. We discussed the age distribution of rapidly growing countries like Mexico. Draw a figure showing the general shape of Mexico's age distribution (labeling axes). Does the country have a stable age structure? Explain how its age structure will affect its future population growth.

No, there is an unstable age structure. As the younger age classes move into reproductive age there will be a large increase in reproductive rate.

3. Give two arguments by Julian Simon about why we should not worry about human overpopulation and three that suggest he is wrong.

Simon

Prices of resources are not going up but down

More brains = more innovation therefore population growth is good

Countries are moving towards more stable age distributions and demographic transitions

He is wrong because:

Per capita levels of many resources (e.g. fish, cropland, forest water) are being reduced

Overall population growth rate is still very high especially in the developing world

As countries improve conditions citizens will make more demands on resources as in the developed world where the impact of each individual is high

Currently available resources are being degraded, e.g. land from irrigation, desertification

Degradation of forests and other habitats needed to support larger populations will reduce the purifying effects of forests on air and water and increase global warming and other effects.

4. Why do genetic traits for kin selection spread in competition with traits that specify only direct reproduction?

Kin selected traits allow for both direct and indirect reproduction whereas direct selection traits only allow that as a more limited reproductive option. Therefore, because of the option to take advantage of high payoff situations that benefit relatives these situations allow for the greater spread of kin selection genes.

5. Describe the special significance of the mother's brother in matrilocal societies, and the evolutionary hypothesis for why this phenomena occurs. Explain how this fits with a general adaptive view of human social behavior.

The mother's brother is an important care and source of inheritance to sisters children. This occurs because men in matrilocal are often gone for long periods and are unable to guard their wives and this leads to low confidence of paternity. Sister's sons may be on average closer relatives than putative sons and thus be the best targets in the next generation for investment. This result is consistent with the idea that kin selection the Bateman effect are important in affecting human social behavior.

6. Describe two different conditions that cause polygyny and explain why polygyny occurs in each instance.

Under conditions where resources important to females are controllable by males and resources are unevenly distributed among males these males may mate polygynously if the quality of their territories are two or more times better than those of other males. If there are no controllable resources and females select males on genetic quality females can share top males genetically (a male can fertilize many males) creating a non-resource based polygyny.

7. How does the Darwinian Anthropologist model support an argument that human behavior can be adaptive even if humans are operating in novel environments?

The DA model suggests that there are several features that guide adaptation. First, there are drives such as the desire to succeed, have success, eat suitable (e.g. sweet) food that drive naive individuals in novel habitats toward adaptively biased behaviors. We have brains that allow use to build scenarios that allow us to construct complex novel strategies to fill desires created by these drives. And we can determine who is successful and copy behaviors that likely make them successful.

8. Draw a logistic growth curve for three populations with different r but the same K on labeled axes. Indicate the areas on the curves where growth is exponential and where growth is zero.

See text

9. Discuss evidence suggesting that both genetic and learned (environmental) components are required for the effective development of passerine bird song.

Young male birds must hear a song sung in order to acquire their own song. If they are deafened thy will be unsuccessful. However they are sensitive to a limited array of sounds during this learning period so that appears to be a genetic program determining when and what they can learn. Males must also practice and if they cannot hear their own song they cannot produce a useful song.

10. What is senescence? Explain its evolution by antagonistic pleiotropy.

Senescence age related designed degradation of a body . Antagonistic pleiotropy says that there is competition among traits that have different payoff age-related payoff patterns. It suggests that traits that trade off good effects early against bad effects late are advantaged against traits that have other patterns (bad effect early and good effects late) because early expressed traits are more valuable that late effect traits are costly. This is because they have the opportunity to affect the individual before and during reproduction, whereas late expressed traits occur after much reproduction and when many individuals have died.

(note I emphasized the difference in death between early and late much more than the difference in reproductive potential so go easy on that part)

11. Describe how the opportunity for exponential growth is related to traits seen in r selected species.

Exponential growth happens in open habitats mostly unoccupied by a species. Traits that allow genotypes their bearers to grow rapidly in those habitats will be a premium and these are seen in r selected species. Early age of first reproduction, large clutches, many small eggs all provide the potential to produce many offspring. Because there is reduced competition things like large egg size and parental care become less important.

12.Why is it important to identify immediate benefits of sex to explain its evolution? Give one example of an immediate benefit for high fecundity organisms.

There are very highly evolved mechanisms associated with sex that are individual adaptations such as fertilization and meiosis. Adaptations can only occur at the individual level if there are benefits at the individual level. Because these occur sex must have individual (immediate) benefits. Immediate benefits could come from either increased genetic variability in offspring or increased disease resistance in offspring.

13. What sex investment ratios are predicted by the Hamilton and Fisher models and explain why the predictions of these models differ?

The Hamilton model predicts female biased sex relate investment ratio (SRIR) whereas Fisher predicts a more even SRIR. This is because in Fisher's model it is an open market in which males compete for mates and the parents success through males is proportional to their investment in them. Because each sex accounts for half of all reproduction population wide male and female investment are equal. Under Hamilton, males are constrained from all out competition so male (and their mother's) success is less dependent on numbers, redundant investment in males is shifted to females for greater overall reproduction.

14. Describe the conflict confronting many females in the kinds of benefits received from mate choice in socially monogamous mating systems. What behaviors might they engage in to resolve his conflict and what are male responses?

Males can provide genetic and material benefits and under monogamy usually male contributions of material benefits (resources) are paramount. Because of the distribution of resources under monogamy many females are forced to mate with the less than the genetically best male thus females appear to compromise genetic for material benefits. Females can engage in extra pair copulations with top males so they can have good genes too. This is not to the advantage of their mate so he is expected to mate guard and attempt multiple copulations to displace sperm.

True/False Questions . Please answer all questions with a clear True of False

1. ___T____Huffaker showed that more complex habitats allowed for greater stability of predator prey systems.

1. ___F____Hamilton's equation 1/r > b/c is a decision rule for when to engage in direct versus indirect reproduction.

3. __ T_____For many traits its important to show no plasticity and not respond to the environment.

4. ___F____Japan and The Netherlands export most crops to sustain their standards of living.

5. ___T____ Death of trees due to flooding is an example of a density-independent effect on population growth.

6. __F_____In population growth models, a lower r will result in a population reaching K is a shorter period of time.

7. ___F____The two elements in Darwin's sexual selection are female choice and phenotypic plasticity.

8. ___F____Imprinting is a very ineffective means of "learning" about who to mate with because sometimes geese imprint on biologists.

9. ____F___Salmon are semleparous reproducers that migrate from the ocean up rivers to breed. They cannot live long enough in out of salt water to return sea so they do all reproduction on their first trip upstream.

10. ___F____Resources are more important than genes in mate choice because there is often no genetic variation among males.

11. ___T____The 2 for 1 cost of sex makes it more difficult for sexual organisms to evolve but this can be mitigated by factors like male parental care.

12. ___T____Sex provides a solution to Muller's ratchet by allowing the creation of undamaged chromosomes by crossing over and then independent assortment allows these chromosomes to be brought together in the same individual.

13. ____T___The current world population is more than 6 billion and its estimated that 3.6 billion will be added by 2030.

14. ___F____In the Lotka-Voltera equation for a the rate of change in prey numbers is, dP/dt = aPNf - qP, where a is the encounter rate between predators and prey.

15. ___T____Strong and persistent selection for reproduction by selfish genes suggests that humane control of world population growth is a difficult to resolve issue..