sexual selection, competition, conflict Flashcards
parts of darwinian sexual selection
male-male (intrasexual)
female choice (intersexual)
anisogamy vs isogamy
aniso: females produce large, high-investment eggs, male tiny, mobile
(bull example
iso: same size
(intermediates lose out)
rule of thumb in sexual selection theory
competitive males
choosy females
what is gamete investment linked to
later parental care
batemans principle (fruit flies) - only males continue to gain fitness after the first mating
male courtship and mating behaviour compete for (and exploit) female investment
females are expected to those males who offer best resources
long-tailed widow bird experiment
females choose longer tails (but these have lower survival
why are females choosy
good resources hypothesis (direct benefits)
Male traits may be a cue to resources that improve female
reproductive success
Nuptial gifts can mediate female choice
hypothesis for male ornaments
fishers “runaway” hypothesis
- mate choice originally evolved to facilitate adaptive choice for traits conferring a survival advantage
zahavis handicap principle
bower bird example
sex role reversals?
pipefish & seahorses
bush crickets (varies)
sexual conflict occurs when…
the optimal outcome of mating is different for males and females
Sexually antagonistic coevolution results as each sex evolves adaptations that bias outcome towards own interests
water striders (female grasping)
sexual conflicts after mating
sperm removal (dragonflies)
sperm displacement (dung flies)
copulatory plugs
sterile helper sperm
anti-aphrodisiacs
life-span reducing proteins (fruit flies)
declined queen vision (honeybee)
what is the model of sexual cannibalism
eat males before: chance of finding another/better mate is high
eat males after: sufficient sperm/extra resources will increase fitnes
males should if: he has mated/chance of remating is low
