Feb 22 lecture handout

Feb 22 lecture handout - Inter-sexual selection Choosey...

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1 Inter-sexual selection Choosey females Female choice occurs, and females make good choices Genetic benefits “Good genes” vs. “sexy son” Fisher (1930) – Runaway sexual selection Initially, males have a trait (e.g., long eye stalks) that provides a benefit. Female preference leads to a double advantage: fitness and attractiveness Positive feedback loop can lead to a maladaptive trait that ensures mating success but not necessarily fitness. “Sexy sons,” but not necessarily good genes Handicap principle (Zahavi 1975) Heritable trait with an energetic cost, reduces viability. ‘High-quality’ males can survive despite the handicap Often expression of the trait is linked to physical condition…degree informs quality “Good genes” hypothesis – this is an honest signal of fitness
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2 Stalk eyed flies: Diopsidae Fit individuals can have greater handicaps They produce larger ornaments Handicap size advertises fitness Receivers' preference for large handicaps is justified Bateman (1948) – a classic study in sexual selection Bateman’s principle: the sex which invests more energy in production becomes a limiting resource for which the other sex competes Therefore, there should be greater variability in reproductive success between the competing sex than the producing sex.
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3 Reproductive success increases for males with increasing numbers of mates, but not for females Model works for some, but not all, mating systems.
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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 22 lecture handout - Inter-sexual selection Choosey...

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