BIOL 3301 ch11 handout

BIOL 3301 ch11 handout - SEXUAL SELECTION Chapter 11 1....

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1 1 SEXUAL SELECTION Chapter 11 1. Males and females differ markedly in size, appearance, and behavior. 2. Examples A. Deer, guppies B. Sexual dimorphism for height in humans (Fig. 11.2) 2 1. Darwin was puzzled by conspicuous traits in one sex that did not appear in the other. 2. Differences between sexes can decrease fitness. A. Long-tailed widow birds (Fig. 11.3) 3 Sexual Selection 1. Sexual selection is the differences among individuals at getting mates (Darwin, The Descent of Man, and Selection in Relation to Sex, 1871). 2. Sexual reproduction creates different selection pressures for females versus males 3. Males and females may not employ the same strategy for maximum fitness
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2 4 Orangutans as an example of differences in parental investment. 5 Asymmetries in Sexual Reproduction, cont. 1. Females provide substantial parental care and males provide none whatsoever in >90% of mammals. 2. Even when females do not care for the young, females make a larger investment in each offspring than males. 3. Female’s reproductive success is limited more by the number of eggs, young 6 Asymmetries in Sexual Reproduction, cont. 1. Access to females will be a limiting resource for most males 2. Access to males will not be a limiting resource for most females.
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3 7 Rough-skinned Newts as an Example of Asymmetric Limits on Reproductive Success 1. Parental investment in both sexes: gametes only. 8
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This note was uploaded on 04/09/2010 for the course BIOL 214 taught by Professor Pepper during the Spring '08 term at Texas A&M.

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BIOL 3301 ch11 handout - SEXUAL SELECTION Chapter 11 1....

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