BIOB51H3 Lecture Notes - Lecture 20: Sexual Dimorphism, Sexual Reproduction, Parental Investment
16 Apr 2016
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Document Summary
Sexual dimorphism: differences in form or behavior of males and females of one species. Frigate birds are dimorphism in color, anatomy, behavior. Explanations for sexual dimorphism: differential natural selection on males vs. females. Darwin"s puzzle: natural selection for survival in a given niche is unlikely to explain many of the differences between the sexes. natural selection for adaptation to niches often similar effect on males and females. Many dimorphic traits can reduce survival: energetically expensive, increase predation risk. Sexual reproduction creates different election pressures on females and males because females generally invest more in each offspring than do males. Parental investment: anything that increases the chance of survival of current offspring while decreasing the ability of the parent to produce future offspring. Female reproductive output is limited by access to resources. Male reproductive output is limited by access to females (eggs) Males but not females, can increase fitness by mating frequency. Males have higher variance in mating frequency than females.
