Biology 3466B Lecture : Evolution Notes

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purplejackal117

3 Feb 2012

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Types of social interactions: the type depends on costs and benefits to actor and recipient, and these are measured in terms of fitness. The actor in any social interaction affects the recipient on the action as well as itself. Cooperative is where both recipient and actor benefit. Selfish is where actor benefits and recipient is harmed. Altruistic is where actor is harmed and recipient benefits. Spiteful is where recipient and actor are harmed. The most common interaction in nature is selfish. Organisms should be looking out for their own reproductive fitness. selfish > cooperative > altruistic > spiteful. Altruism results from kin selection and is kind of a selfish form. Examples of altruism: cooperative breeding large group that raises offspring together (ex. seychelles warbler, white-fronted bee-eater). Alarm calling helps colony mates so they can hide from predator, but the one doing the calling is put at risk (black-tailed prairie dogs, belding s ground squirrels).

Related Questions

Thinking of behaviours an organism can adapt, at the very basean action can always be either selfish or altruistic(cooperative).

Usually, selfish behaviour is assumed to be the preferred choiceand the question is how altruistic behaviour comes about.

But if reciprocal altruism can give both participants a higherbenefit than their respective costs (which it usually does), whywould selfish behaviour (in the sense of behaviour which reapsbenefit at another entity's expense) be what we assume to happen?If evolution tends to optimise things, why does it not optimisethis?

Eusociality, particularly focusing on the presence of certainaltruistic sterile organisms within the social set-up createsquestions as to why would the process of natural selection havefavoured the persistence of such genes especially in hymenoptericspecies. One explanation (provided probably by Hamilton)pertains to very similar genetic constitutions of females of suchspecies (owing to haploid nature of males), which increases geneticsimilarity between the female members of the social group. Thus itwould be more "beneficial" (i.e., favourable for the persistence ofsimilar genetic builds) for a female worker to help the fellowsiblings, to which it bears greater genetic similarity, than itsown offspring to which it bears a lesser genetic similarity. Thismight in a deeper way explain altruism in case of hymenopteranswhere the male is a parthenogenetic haploid and the female isdiploid.

But why would the sterile condition of the workers in case ofalmost all eusocial groups be favoured by natural selection ongrounds that it improves the 'fitness' of the 'genetic build' ofthe workers and ultimately the sterile altruists benefit thepersistence of its genetic traits? Moreover the altruistic natureof the haploid males also goes unexplained.

Present and discuss the core elements of Darwin's theory of evolution by means of natural selection. As potent as the theory proved to be, discuss why Darwin and his immediate followers found it so difficult to explain adequately the emergence and persistence of apparently altruistic behaviors (i.e., behaviors resulting in an organism's reporductive self sacrifice) in various social species. Be sure to include reference to at least three types of altruistic behaviors in the the response to the aspect of this question.

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Biology 3466B Lecture : Evolution Notes

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