1. Why may animals behave altruistically to their kin?
- Introduction outlining the traditional theory of group selection, where animals behave in a certain way
for the good of the species. Wynne-Edwards
- Explain how this has been disproved by David Lack, who studied the clutch sizes in birds
- Lead into Dawkins theory of gene selfishness and the idea of genes wanting to get more numerous in
the gene pool
- Explain how genes can exist either in your body or in the body of a relative
- Explain the idea that a gene can therefore propagate themselves into the next generation either by
reproducing themselves or helping their relatives to reproduce
- Therefore what appears to be altruism is in fact driven by gene selfishness
- Explain the index of relatedness
- Describe situations where extreme suicidal altruism benefits the genes
- Give examples of apparent altruism seen in nature: worker bees, naked mole rat, alarm calls of birds.
- Conclusion summing up the Selfish Gene theory and how it can explain apparent altruism
2. Do unrelated individuals ever cooperate with each other?
- Introduction outlining the Selfish Gene theory and Kin selection (described in essay above)
- State that there are some situations where relatedness cannot be used to explain co-operation
- There are 3 hypotheses for this behaviour:
- 1) mutualism were two individuals cooperate simply because each gains a net benefit from such behaviour
e.g. hyenas hunting in packs
- 2) manipulation where the donor has been manipulated by the recipient e.g. the cuckoo
- 3) reciprocity i.e. A helps B today and then B helps A tomorrow
- Use Prisoners Dilemma model to explain how this become ESS if individuals interact an indefinite number
of times i.e. Tit for Tat
- Explain how Tit for Tat is not strictly speaking an ESS but can gain a foothold in a population through
a) genetic kinship and b) clustering
- Describe examples for reciprocal altruism seen in nature: ants and aphids, vampire bats and cleaning
- Conclusion, summing up that reciprocal altruism is commonly seen between unrelated individuals but
ultimately because the altruist can benefit in the long run from such behaviour
3. How do females choose males to mate with?
- Introduction explaining the difference in gamete size between egg and sperm and thus the importance
of selecting a good mate
- Explain why male would tend to abscond because of the selfish gene selection pressures that would
want him to mate with as many females as possible to benefit his genes
- Two ways in which the female can prevent being left with the sole responsibility of the offspring the
Domestic Bliss strategy and the He-man strategy.
- Domestic Bliss = tries to spot signs of fidelity and domesticity in advance. Forces the male to invest
more before copulation so that it does not pay him to abscond after
- Give examples from nature e.g. nest building, courtship feeding rituals
- He-man strategy = resigns herself to rearing the child on her own and chooses mate solely on his "good
genes". Can tell these by strong muscles, long legs, attactiveness etc
- Discuss the Handicap principle (Zahavi) indicates male can survive in spite of handicap
- Examples include lekking blue peafowl, long-tailed widow birds, three-spined stickleback and house
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