Exam Review

• “Need”, “want” and “try” are all words to be careful with (or avoid!) in explaining evolution…

• “Need”…

Will he get one?Will his species get one?

A quote about “wanting” from one of my favorite evolutionary biologists:

• Picture title: “Elafins do not want a loin to git biger.”

• i.e., Elephants do not want lions to get bigger…

• Connor Demastes

• Question # 18: For what reasons are females attracted to flashy males… What advantage may she gain?– “Females want to have sexy sons”…– Wanting or trying may not matter to the process– Conscious decisions not necessary

W. D. Hamilton, Oxford UniversityOn 7 March 2000, William Donald Hamilton died in Oxford, England, from malaria contracted during a field expedition to the Congo. With his death, the field of evolutionary biology arguably lost its greatest practitioner since Charles Darwin. W. D. Hamilton made major contributions to many areas of evolutionary biology, but perhaps his greatest impact was on the discipline of behavioral ecology. The topics that he focused his energies upon include kin selection, reciprocity, sex-ratio selection, the evolution of senescence, alternative reproductive strategies, selfish gains of group living, haplodiploidy and the evolution of eusociality, parasite-host arms races, and the role of parasites in both mate choice and the evolution of sex.

Hamilton may have taken his ideas from nature, but he developed his hypotheses in the form of rigorous mathematical models. In an interview with Frans Roes, he said: “Often I use mathematics because I need to straighten out my own ideas. I have a somewhat illogical brain, and unless I put it through the mill of mathematics, I can continue to believe in the impossible for a long time” (International Society of Human Ethology Newsletter, vol. 12, 1997, pp. 3-7).

Hamilton’s Rule:• When altruism can be favored by natural selection:

• B = benefit to recipient• R = relationship coefficient• C = cost to donor

• If B * r > C, then selection can favor altruism• The donor benefits from the relative benefiting

• Altruism = the actor suffers a cost to benefit the recipient

• Natural selection should eliminate tendencies for altruism unless the actor actually benefits in some way (indirect fitness, reciprocal altruism)– Non-breeders in naked mole-rats or bees– Prairie dog that dies to save kin– Mother Teresa and tipper at restaurant?

Hear it

Kinship matters to prairie dogs

Prairie dogs modify behavior by situation

Eusociality, not utopiaQueen maintains dominance through hormones, threats, shovingSuccessful strategy, possibly explained by high inbreeding (high coefficient of relatedness)

http://cns.uni.edu/~spradlin/evolution/Section3.html

High female mortality on nestsMale biased sex ratioNot enough females to go aroundFemales disperseMales more philopatric

• Linda studied the birds in a botanic garden• Birds were habituated to people• Sat quietly 5-10 feet from nests and recorded

feeding behavior in banded birds.• DNA used for paternity analysis.• Figs. 1 and 2 are used to explain paternity analyses.• Focus on Intro, Discussion, and Fig. 3!