BIOL 210 Lecture 12: 12sexualselection.pdf
28 Oct 2014
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Larger females enter arena first, get a jump on breeding, match up with better quality males. Get a head start, and produce more offspring by virtue of their size (simple model!) Intrasexual competition: darwin saw ss operating in two ways, the first being intrasexual competition for mates. In intrasexual selection, members of the competitive sex, usually the male (but see ex. Intrasexual selection: how the giraffe got its long neck: classic story: giraffes with longer necks were able to forage on (acacia) treetops during dry season (out of reach of other grazers) Selection therefore favoured the long necks: very expensive structure / spectacular example of adaptive evolution. Sexual selection important in maintaining the neck of the male giraffe. Very poor fossil record: little direct data on trait evolution: evaluating evolution of the giraffe neck can only be done using logic, observation, and the comparative method.
