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BIOL 336 > Adaptations & Traits 3 > Flashcards

Adaptations & Traits 3 Flashcards

1
Q

sexual cooperation (2)

A
  • when males and females share a reproductive interest in combining gametes
  • females need access to sperm; males need access to eggs
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2
Q

sexual conflict (2)

A
  • describes the divergent interests males and females have for sex
  • both sexes have adaptations that take control over reproduction
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3
Q

sexual conflict: what are males selected for (3)

A
  • to mate with female regardless of whether she’s fully ready
  • to fight off other males or their sperm
  • to induce females to invest in their offspring
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4
Q

sexual conflict: what are females selected for (3)

A
  • mate only when they have the resources to support eggs/babies, and only as often as she needs
  • mate with multiple males to have more diverse babies or to have sperm to select from
  • hold back some investment for a future brood
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5
Q

sexual antagonistic coevolution (2)

A
  • describes the arms race between sexes for adaptations to have better control over reproduction
  • balance of cooperation and conflict
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6
Q

sexual selection: mate selection -> mating

A
  • when the female “chooses” whether she wants to participate in mating with a male
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6
Q

sexual selection: mate selection -> mating

A
  • when the female “chooses” whether she wants to participate in mating with a male
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7
Q

sexual selection: mating -> zygote (2)

A
  • whether the female allows the male sperm to fertilize her egg
  • whether the male sperm is able to outcompete sperm from other males
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8
Q

sexual selection: zygote -> adult offspring

A
  • whether the mother invests a lot of resource into the males offspring or not
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9
Q

cryptic female choice (2)

A
  • sexual selection that occurs after mating and is not easily visible because it occurs within her body
  • describes how the females decision is not complete just because she allows the male to copulate
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10
Q

how can a female choose to reject a male after copulation has occurred? (5)

A
  • dump the sperm
  • don’t transfer the sperm to the right pace in the body
  • re-mate so the second male’s sperm competes
  • doesn’t ovulate
  • doesn’t mature the eggs
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11
Q

isogamy (2)

A
  • same-size gametes

- 2 mating types, called plus and minus

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12
Q

anisogamy (2)

A
  • some gametes are really big (eggs), some are really small (sperm)
  • animal and land plants and anisogamous
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13
Q

what does the difference in gamete size mean? (2)

A
  • eggs are costly, sperm are cheap
  • females have a larger consequence for choosing the “wrong” male as this could lead to relatively long term and large investment in unfit offspring compared to males
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14
Q

male-biased operational sex ratio (2)

A
  • describes a mating pool where there are more males than females
  • leads to more males competing for fewer females
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15
Q

why are operational sex ratios male-biased (2)

A
  • females are tied up growing eggs, tending babies, etc; they aren’t in the pool of available mates all the time
  • males are always looking for another mating; they are in the pool of available mates all the time
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16
Q

why do females tend to be more choosy than males (2)

A
  • females don’t compete as much: they can afford to reject males because there are plenty more males in the mating pool
  • females suffer a higher cost of a mistake: her investment per mating is likely higher than his
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17
Q

variance in reproductive success: males (2)

A
  • have a relatively greater variance

- some males mate a lot, whereas others don’t at all due to competition

18
Q

variance in reproductive success: females (2)

A
  • have a relatively smaller variance

- females are more or less assured of some offspring, as long as they are healthy, because there is little competition

19
Q

intrasexual selection

A
  • males compete amongst each other and females mate with the winner
20
Q

intersexual selection

A
  • females choose among males according to their qualities
21
Q

types of intersexual selective forces (4)

A
  • direct benefits
  • good genes, honest signals
  • sensory bias
  • runaway
22
Q

direct benefits hypothesis (2)

A
  • females are selected to choose males that give them resources or protection
  • these direct benefits ensure the females can survive and reproduce and means that her genes have a better chance of getting into the next generation
23
Q

direct benefits hypothesis: prediction

A
  • males that offer more resources/protection are given a better chance to mate
24
Q

good genes hypothesis (3)

A
  • females are selected to choose males with good genes, because her offspring will then do better with these genes
  • her genes will be in a good collaboration, building offspring bodies that survive and reproduce well
  • not a direct benefit to her, but to her offspring instead
25
Q

good genes hypothesis: prediction

A
  • females should prefer traits if the presence of those traits in the males is correlated with/predicts him having good alleles for survival/reproduction, even if they don’t have direct benefits to her
26
Q

honest indicator (2)

A
  • an indicator trait that is costly to the male, and thus harms the male/lowers his survival rate
  • females are selected to choose this harmful indicator trait because its stupid; its costliness guarantees that only high quality males can afford to make it
27
Q

dishonest indicator

A
  • a trait that any male can make; a trait that won’t predict male quality and is not useful for females to choose
28
Q

why is a peacock tail an honest indicator

A
  • its elaborateness is a sign of how much the male can afford to waste
29
Q

sensory bias (2)

A
  • female bodies and nervous systems are strongly selected for them to find food, avoid predators, and live life
  • males have to “please” these bodies and those nervous systems
30
Q

sensory bias hypothesis (2)

A
  • first, ecological selection: different populations evolved different preferences
  • then sexual selection: later, males take advantage of this attraction that females already have to the trait from ecological selection by evolving more exaggerated version of this trait
31
Q

sensory bias hypothesis: guppies (2)

A
  • first, ecological selection: different populations evolved different preferences for orange in food (algae, fruit, etc)
  • then sexual selection: later, males take advantage of this attraction that females already had to orange (for feeding) by evolving bigger orange spots to attract females in another context (mating)
32
Q

how is sensory bias different from the good genes hypothesis (3)

A
  • males evolve bright, shiny “bling” to take advantage of biases in female sensory systems that evolved previously for other reasons
  • the “bling” mimics signals that really do matter to the female (fruit, fire, etc)
  • attraction may be a simple sensory attraction, and may not help the female choose a good quality mate
33
Q

runaway sexual selection (2)

A
  • once a population has alleles for a male trait and a female preference, a positive feedback loops can drive these alleles to fixations, regardless of how useful/indicative they are
  • occurs because a linkage disequilibrium develops where the male trait allele and female preference allele occur together more often than expected by chance
34
Q

what type is selection is runaway selection (2)

A
  • frequency-dependent selection: the strength of selection on an allele depends on the frequency of the allele
  • as frequency of choosiness rises, the selection for the male trait rises, which means that the selection for choosiness increases
35
Q

what occurs as runaway selection proceeds, generation by generation (3)

A
  • linkage disequilibrium gets stronger
  • average preference of females increases
  • male trait increases in frequency
36
Q

runaway sexual selection: prediction (2)

A
  • in a population with variable male traits and female preferences, there should be signs of linkage disequilibrium
  • families should tend to have female preferences that match their male traits
37
Q

what stops the runaway process of escalating the male trait and the female preference? (2)

A
  • there may be no more genetic variability

- it may be too costly to produce the trait, so natural selection for survival stops the runaway

38
Q

steps in runaway sexual selection (3)

A
  1. variability in male trait & female preference for it; non-choosy females are agnostic
  2. agnostic females mate indiscriminately; choosy females mate more with males with the trait, rising its frequency and generating a linkage disequilibrium between the alleles
  3. with each subsequent generation, the linkage disequilibrium gets stronger, the average preference of females increases, and the male trait increases in frequency
39
Q

are the mechanisms for sexual selection by female choice mutually exclusive?

A
  • no, more than one mechanism can be acting at the same time
40
Q

when do the benefits occurs: direct benefits

A
  • in her generation and to her directly, or to the resources she gives to her offspring
41
Q

when do the benefits occurs: good genes

A
  • in the next generation: to her offspring via the genes they will inherit from the male
42
Q

when do the benefits occurs: sensory bias

A
  • there may be no benefit at all
43
Q

when do the benefits occurs: runaway

A
  • there may be no survival/fecundity benefit at all, although the genes are selecting themselves, because of linkage disequilibrium

BIOL 336 (13 decks)

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