Anthro Lecture 2-5

Anthro Lecture 2-5 - Anthro Lecture 2/5 I. Is sex-biased...

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Anthro Lecture 2/5 I. Is sex-biased dispersal an adaptation to avoid inbreeding? a. In most mammals, including most primates, males are the dispersing sex b. Prediction: if sex-biased dispersal functions to prevent inbreeding, then female dispersal will occur when males continue breeding in the same group long enough that they risk mating with their daughters c. Alternative hypothesis i. Males are usually not the dispersing sex because they’re forcibly expelled from their natal group at adolescence ii. Generally not supported d. Is inbreeding avoided when adult-opposite sexed kin are co-resident i. In primate groups, matings between maternal kin (e.g. maternal half- siblings, maternal aunt-nephew pairs) are always rarer than expected by chance ii. E.g in rhesus macaques, most males disperse, but some breed in their natal group. But they almost never copulate with their matrilineal kin iii. Female rhesus macaques stay away from their male matrilineal kin while in estrus II. How do monkeys “know” who their kin are? a. The Westermark hypothesis: close childhood companions develop sexual aversions to each other b. In rhesus macaques, like most primates, maternal kin form close social bonds from early in life c. Some research on monkeys show no inhibition of close kin mating among paternal kin, who don’t necessarily have close bonds in early life d. Phenotype matching: animals could, theoretically, check whether another animal’s phenotype (appearance, odor…) is similar to their own, and then use this as a cue to relatedness e. Some evidence from rhesus macaques and savanna baboons that paternal half- sisters associate preferentially f. Age proximity as a cue?
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g. How do capuchins, with long male breeding tenures and female philopatry, avoid father-daughter inbreeding? h. Alpha males sire most offspring of females other than their daughters, but subordinate males sire almost all the offspring of the alpha’s daughters III. Hypothesis a. The relationship between dominance and female reproductive success depends on whether there’s strong contest competition (direct confrontations) for food i. This depends on the distribution of the species’ food sources ii. Food can limit RS: e.g in Japanese macaques, population growth is linked to provisioning b. Savanna baboons feed on corms: clumped valuable food c. Mountain gorillas: wild celery – superabundant, low value
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Anthro Lecture 2-5 - Anthro Lecture 2/5 I. Is sex-biased...

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