Altruism in viscous populations revisited: competition and altruism do not exactly cancel even in the island model

作者：Whitlock Michael C^*; Van Dyken J David

来源：Evolutionary Ecology Research, 2011, 13(7): 747-752.

• altruism
• competition
• cooperation
• inclusive fitness
• island model
• viscosity

Background: Hamilton suggested that cooperation would evolve most readily in viscous (low dispersal) populations, because nearby individuals would have high genetic relatedness. However, Taylor (1992) found that the indirect fitness gains achieved by cooperation with relatives is exactly offset by local competition, preventing true altruism from evolving no matter the degree of relatedness or population viscosity.
Question: Does local density regulation exactly cancel the indirect fitness benefits of altruism in Taylor's model?
Mathematical method: Inclusive fitness theory following the derivation of Taylor (1992).
Key assumptions: Relatedness depends on the effective deme size, N-e, but the distribution of fitness benefits depends on its census size, N.
Conclusions: For Taylor's model, the exact cancellation of the indirect fitness benefits of altruism by local competition requires the special case where N-e = N, a condition not often observed in nature. Even in Taylor's model, the benefits of altruism depend on relatedness, rather than just direct benefits. When N-e < N, as is commonly observed, true altruism can evolve, and it is more likely to do so when populations are more viscous. Local competition is important, but it requires restrictive conditions to exactly negate the effects of cooperation among relatives in a viscous population.

• 出版日期2011-10