Sexual selection

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what are Tinbergen's 4 Q's?
1) Causation 2) Development/ontogeny = proximate-how 3) Adaptive advantage/function 4) History/phylogeny = Ultimate-why
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Give examples for Tinbergen's
1) females synchronous in oestrus causal = chemical cues? take over by males functional = better cub survival 2) young die with new males causal = abortion or infanticide function = oestrus quicker + reduce comp for young
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How are hypotheses tested?
1) experiments 2) comparative = inter-/intraspecific
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Give example for the comparative method
breeding in gulls + predation risks -black-headed gulls = ground = clean -kittiwakes = cliff = messy
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what does isogamous mean? and what organisms?
equal sizes = unicellular
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what does anisogamous mean? and what organisms?
unequal sizes = plants+animals (egg = 85000x vol of sperm)
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what evidence is there for sexual selection- with examples?
male weaponry e.g. elephant seals (5/180 = 50-90% matings) female choice e.g. widow birds + sedge warblers
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why are females choosy?
1) good resources 2) good genes
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examples for good resources
widow birds, warblers + N. American Bullfrog (Rana catesbeiana) = territory hanging flies (Hylobittacus apicalis) = food gift
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examples for good genes
attractive sons (Fisher) = widow birds - runaway selection & stalk-eyed flies (Cyrtodiopsis dalmanni) & Zahavi's handicap principle = peacocks (Pavo cristatus)
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criticisms for the handicap principle
handicap = expressed in good + bad conditions & reduces variability
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what is the Hamilton-zuk hypothesis? with examples
selection for handicaps will increase resistance in the future e.g. 3-spined sticklebacks (Gasterosteus aculeatus) redder males -= healthier
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what is sex role reversal and when does it occur?
males become choosy if they invest highly or if female competition for males is high
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what are the processes for sperm competition?
competition between sperm and female cryptic sperm choice
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why do females copulate with multiple males?
cost of resistance exceeds acquiescence (harassment + infanticide) or benefits from resources or genetics (EPC's)
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example for sexual conflict - over mating
water striders = antagonistic co-evolution of male grasping and female resistance
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example of sperm removal
male damselflies/dragonflies - remove rival sperm before depositing own
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example of sperm displacement
male dung flies flush out previous males
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example of copulatory plugs
orb-web spiders detach 1 palp to plug
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example of anti-aphrodisiac
butterfly (Heliconius erato) deposit scent on females
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example of seminal fluids (Accessory gland proteins-ACPs)
Drosophila melanogaster sperm contains proteins that alter female behaviour/fitness = incapacitate rival sperm, increase egg laying rate or decreasing propensity to remate
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example of strategic allocation of sperm
feral fowls (Gallus gallus) choose to allocate more to females that lay larger eggs, investment decreases with repeated mating with same female but increases with novel female = Coolidge effect
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Card 2

Front

Give examples for Tinbergen's

Back

1) females synchronous in oestrus causal = chemical cues? take over by males functional = better cub survival 2) young die with new males causal = abortion or infanticide function = oestrus quicker + reduce comp for young

Card 3

Front

How are hypotheses tested?

Back

Preview of the front of card 3

Card 4

Front

Give example for the comparative method

Back

Preview of the front of card 4

Card 5

Front

what does isogamous mean? and what organisms?

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