Feb 15 handout - Sexual Selection Sexual selection...

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1 Sexual Selection • Sexual selection “depends, not on a struggle for existence, but on a struggle between males for possession of the females; the result is not death to the unsuccessful competitors, but few or no offspring.” – C. Darwin, Origin of Species Sexual Selection • Selection of traits (usually of males) that do not improve chances of survival, but do improve chances of mating. Sexual Selection • Why does it happen? – Parental Investment –Sex ra t io – Mating systems • What are the outcomes? – Sexual dimorphism
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2 Types of Sexual Selection • Male-male competition intrasexual selection • Female choice intersexual selection, also called epigamic selection Darwin’s Observations • Males are very eager to copulate with any females. • Females appear to be passive and exert choice over the males with which they mate. Parental Investment • Female Investment – Large gamete (egg) – Time of egg development – Oviposition risks – Care of offspring
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This note was uploaded on 03/21/2012 for the course ENTOMOLOGY 104 taught by Professor Lewis during the Spring '12 term at UC Davis.

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Feb 15 handout - Sexual Selection Sexual selection...

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