CAS AN 263 Lecture Notes - Lecture 5: Operational Sex Ratio, Mangabey, Parental Investment
6 Feb 2018
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Document Summary
Intrasexual competition: competition among members of one sex for member(s) of the opposite sex, classically, called male-male competition. Two ways to compete: physical/direct competition, scramble/indirect competition. Direct competition among males: large body/sexual dimorphism, weapons, aggressive behaviors. Factors affecting the intensity of competition: relative difference in parental investment between sexes, competition more intensive when one sex invests a lot more than the other sex, the operational sex ratio: Indirect competition among females: establish best core area, core area competition hypothesis: core area with better food leads to better reproduction; high-ranking females get best core areas, so they have higher reproductive success. Chimps: core areas in neighborhoods (some better than others: female ovarian hormones are higher in high-quality neighborhood, females have faster reproductive rate in high-quality neighborhood. Improved offspring survival in high-quality neighborhood: problems with gaining group membership in core areas, dispersing females more susceptible to predation, location of food sources unknown.
