Alternative Reproductive Tactics in Birds: Individual Variation in Clutch Size

摘要: Clutch size in birds varies considerably among individuals within a population and given year. I consider three hypotheses which may account for the maintenance of this variation: (I) Individual optimization. Birds are assumed to adjust clutch according their ability rear young. Those able successfully large do so; those not so able, it is maintained, best (with respect fitness) by rearing small clutch. The hypothesis views variation as conditional evolutionarily stable strategy (ESS). (II) Tradeoff survival. Different sizes produce equivalent “payoffs” (in terms because tradeoff between offspring survival adult posits mixed ESS with size. (III) Year-to-year fluctuations selection pressure. Selection favors different years; these essentially unpredictable. changes (genotypically) from year result regime. does posit evolutionary stability, i.e., populations genetic equilibrium.