11 Evolution of Cooperation Exam #2.pptx - Previously on...

This preview shows page 1 - 21 out of 56 pages.

Previously on Human Origins…
Chimpanzee Baboon Bonnet macaque
marmoset tamarin
Peacock
Lecture 11: The Evolution of Cooperation The problem with cooperation Kin selection Reciprocal altruism Nepotism in primate groups
Actor’s Fitness Recipient’s Fitness Selfish + ̶̶ Mutualistic + + Altruistic ̶̶ + Spiteful ̶̶ ̶̶
C. Stanford
J. Manson
Altruism not normally favored by selection Assume: groups of 9 monkeys Two genetic variants Callers give alarm call when they spot predator Noncallers remain silent Population is 25% callers and 75% noncallers Alarm calls are altruistic listeners warned more likely to escape the predator callers more conspicuous less likely to escape the predator
Altruist gives alarm call Non-altruist doesn’t give alarm call + + + + + + + + +
Indiscriminate altruism not favored because altruists receive same benefits as non altruists Caller’s group contains same number of altruists as noncaller’s group Hearing call doesn’t affect relative fitness of altruists Calling reduces relative fitness of caller Altruists are selected against
Thomas Hobbes
Lecture 11: The Evolution of Cooperation The problem with cooperation Kin selection Reciprocal altruism Nepotism in primate groups
Interaction among relatives is nonrandom Suppose that animals live in groups of full sisters Then, from the rules of meiosis one half of the recipients will carry the same gene as the caller one half of the recipients carry genes randomly sampled from the population
A Ego has the A allele Prob sister gets copy of A from mom Pr(from mom) = ½ Pr = ½ A
A A Ego has the A allele Prob sister gets a copy of the same A from the same parent Pr(from mom) = ½ If so, Pr(sister is A) = Prob(both from mom) = ½ ½ = ¼ Pr = ½ Pr = ½ A
A A Ego has the A allele Prob sister gets a copy of the same A from the same parent Pr(from mom) = ½ If so, Pr(sister is A) = Prob(both from mom) = ½ ½ = ¼

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture