Biology 106 sexual selection notes

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  1. sexual selection
    • heritable differences expressed in phenotype
    • type of natural selection (differential fitness and thus differential allele frequencies)
    • mating is not random (more or better mates)
    • traits involved change reproductive opportunities (fertilization and male acquisition)
  2. Intersexual selection
    • between one sex and the other (other sex makes choice- usually females)
    • impressed or not?
    • Ex: blue footed booby, sage grouse, peacock
    • Lek- males gather in common area to win female attention
  3. Intrasexual Selection
    • competition and selection among individuals in the same sex
    • Ex: dominance- gets you access to mates, territory (seal, ram)
    • access- able to get mates (post mating competition- crabs)
    • territories- not all fighting (bird songs indicate territory)
  4. Cryptic Sexual Selection
    • what happens to sperm after mating
    • Ex: when females mate with 1> male (pollen)
  5. When is selection on sex/reproduction not sexual selection?
    • more/better matings +choice= sexual selection
    • not mating+acts on both sexes+ side effects of natural selective pressures= natural selection
    • certain naturally selected traits can be useful for sexual selection
  6. Males more affected than females? Why?
    • reproductive success variable
    • dominant males control access and resources
    • pay-offs are variable
  7. Sexual dimorphism
    • females and males look different
    • can be both natural and sexual selection
    • Ex: hair, insect genitalia, wasp (ovipositor)
  8. signals
    • shows fitness of the male to females
    • costly signals are HONEST- females pick for real fit males, not unfit males that fake it
    • Ex: small deer with huge antlers doesn't signal health because the signal is too costly
    • Ex: carotenoids (bright orange beak)
    • - concept: I've got a surplus of carotenoids so I can afford to waste them
  9. symbolic fights
    • symbols in place of actual weapons
    • Ex: arms race, weapons display rather than waste energy, risk injury
  10. Woodpecker example
    woodpeckers can amplify sounds with gutters, can fake the signal
  11. handicaps
    • signal is so costly, continued survival is highlighted
    • Ex: giant antlers, size, armoring
  12. sensory bias
    • arbitrary signal that imitates food, other important factors
    • opposite sex who can see it faster will mate with them
  13. runaway selection
    selection caused once reasonable signal to get too big
  14. Sexual Selection and Species Fitness?
    not always in line because constly signals both hurt species fitness and increase reproductive opportunities
  15. Sexual Selection and Trade-offs?
    • being too attractive will hurt survival after a certain point
    • Ex: bull frog and croak being eaten by bats
  16. Horns example
    • big horns allow control over harem, mates
    • copulatory organ is smaller, however
  17. Fungi (cordyceps) example
    • ecological impact
    • fungi take over minds of moths, flies, and ants
    • there is a limited repertoire of chemical receptors and some coincidental matches!
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Biology 106 sexual selection notes
BSCI 106 sexual selection notes, concepts, etc
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