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Unformatted text preview: f(A) increases. Model this as follows: assume a haploid trait with A=altruist, a=selfish; p=f(A). In each population p decreases within a population through time due to selfish individuals out competing altruistic individuals. But in all populations as a whole the altruist gene increases over time. Below, the average f(A) across all populations is 0.5 at the start: Clearly, if this system were to continue for many generations, the frequency of the altruist gene would decrease within each population. But under conditions where the selection favoring selfish genes was weak and the group selection increasing the probability of staying extant (or the growth rate of the population) was strong, and altruist allele might be preserved. Because the conditions are so restrictive, group selection is presumed to be a rare phenomenon....
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- Fall '10