Feb 17 handout - Mating Systems Polygyny: males mate with...

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1 Mating Systems Polygyny : males mate with more than one female in a lifetime Monogamy : males and females mate with only one individual of the opposite sex in a lifetime Polyandry : females mate with more than one male in a lifetime • Mating systems of polygyny, polyandry, promiscuity, and monogamy with inequality of the sexes lead to sexual selection. • Darwin proposed male-male competition, and intersexual selection of males, was common because it was produced by the most common mating systems in animals – Monogamy coupled with excess of males –Po lygyny Types of Sexual Selection • Male-male competition intrasexual selection • Female choice intersexual selection, also called epigamic selection
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2 Intra-sexual selection “Ardent” males Male fighting Plecia nearctica Diptera: Bibionidae Love bugs – males hover to capture emerging females If you are hovering to capture females to mate, where is the best hovering location?
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3 Males compete • Males emerge before females (protandry) • Females emerge from decomposing leaves and soil and fly upward into the male swarm • Large males are more successful than small ones Intra-sexual selection “Ardent” males ardent: characterized by warmth of feeling typically expressed in eager support or activity Sperm competition – prevent other males’ sperm from fertilizing eggs Spermatheca Sperm removal, genital cement, anti-aphrodisiac scents Single mating event (monogamy) vs. Multiple mating, guarded in copula Sperm competition in Odonates
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4 Mate Gaurding Xylocorris maculipennis Males pierce female, inject sperm into body cavity, some fertilize eggs Males may also pierce other males, who then fertilize with the piercing males sperm Anti-aphrodisiac scents Heliconius erato Males deposit scents on females at end of mating, similar to a territorial scent used to repel other males
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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 17 handout - Mating Systems Polygyny: males mate with...

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