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Principals of Evolution > Life History Evolution > Flashcards

Life History Evolution Flashcards

1
Q

life history

A

an individuals patterns of allocation. throughout life, of time & energy to various fundamental activities such as growth, body repair, metabolism, & reproduction

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2
Q

lifetime reproductive success

A

the number of offspring produced by an individual in their lifetime

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3
Q

trade offs

A

inescapable compromises between traits that limit their evolution

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4
Q

life history examples

A
  • some species mature early & reproduce quickly, others mature late & reproduce slowly
  • fundamental trade-off between offspring size & number
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5
Q

life history examples: some species mature early & reproduce quickly, others mature late & reproduce slowly

A
  • female deer mice mature at ~7 weeks & have 3-4 litters of pups each year
  • female bear mature at 4-5 years & have pups every 2 years
  • some trout reproduce multiple times, but salmon reproduce once & die
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6
Q

life history examples: fundamental trade-off between offspring size & number

A
  • the oyster releases 10-50 million eggs in a single sperm, each very tiny
  • the clam broods <100 eggs, each very large
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7
Q

life history in blue footed boobies

A
  • in males, feet range from dull blue to bright green
  • females prefer bright green feet
  • maintaining bright feet gets harder as the birds age
  • males that take a year off from reproduction have brighter feet
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8
Q

the ideal organism

A
  • mature at birth
  • continuously producing a large amount or large offspring
  • live forever
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9
Q

Brown Kiwi

A
  • females weight ~6 lb
  • 1 lb egg
  • only 1 egg is laid at a time
  • high quality
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10
Q

Sea Urchins

A
  • females take a few years to get to a reproductive age
  • lay 100,000-200,000 eggs at one time
  • all very tiny with very small chance of success
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11
Q

Thrip egg mites

A
  • mites that eats the eggs of a small plant eating insect called a thrip
  • females mate with their brother in womb, then eat their way out of mom
  • born mature, live 4 days
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12
Q

energy allocation in the Virginia Opossum trade offs

A
  • a different female that begins reproducing sooner will be smaller & have smaller litters, but may be likely to actually reproduce
  • a female that allocates more to tissue repair will have less to give to reproduction, but may live longer
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13
Q

energy allocation in sand crickets

A
  • short winged females devote more of their energy to reproduction & will produce sooner, but can’t disperse well
  • long winged females devoted more energy to flight muscles, but reproduce later in life
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14
Q

senescence ________ an individuals fitness

A

reduces

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15
Q

senescence

A

a decline with age in reproductive performance, physiological function, or probability of survival

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16
Q

longevity evolves: 2007

A

Eskimo hunters killed a bowhead whale & found in its flesh a kind of harpoon that was used only around 1890

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17
Q

longevity evolves: 1999

A

growth patterns in the teeth of a bowhead whale suggests that it is 211 years old

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18
Q

The Evolutionary Theory of Aging

A
  • mutation accumulation hypothesis
  • 97% of all offspring in the population are produced by individuals ages 13 or less
  • selection on late acting mutations is weak
  • an individual with a mutation that kills them at age 2 has 0 fitness
  • selection on early acting mutations is strong
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19
Q

mutation accumulation hypothesis

A

mutations that impact fitness late in life are under weak selection

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20
Q

if inbreeding depression is caused by deleterious alleles and late-acting deleterious alleles are at higher frequency under mutation-selection balance because selection is weaker on deleterious alleles, THEN…

A

severity of inbreeding depression should increase with age

21
Q

houseflies aging

A

in houseflies that are allowed to reproduce for 5 days only, longevity quickly declines because late-acting mutations accumulate

22
Q

why is the relationship the same for large & small populations?

A

given neutral evolution, the rate of substitution is equal to the mutation rate: K = u

23
Q

in a diploid population, the number of new mutations per generation at a locus =

A

2NeV

24
Q

2NeV variables

A
  • Ne = number of copies of a gene
  • V = mutation rate of new selectively neutral mutations per gene copy per generation
25
Q

for a neutral mutation, the probability of fixation =

A

1/2Ne

26
Q

the rate of substitution at a locus K:

A

2NeV * 1/2Ne = V substitution/generation

27
Q

pleiotropy

A

when a single gene influence multiple traits

28
Q

antagonistic pleiotropy

A

when the alleles at a locus have fitness benefits & costs

29
Q

the antagonistic pleiotropy hypothesis for senescence

A

mutations conferring fitness benefits early in life & fitness costs late in life will be under positive selection when the benefits outweight the costs

30
Q

is pleiotropy common or uncommon?

A

very common

31
Q

frizzle mutation in chickens

A

feathers curl outward instead of lying flat against the body

32
Q

other effects of the frizzle mutation in chickens

A
  • higher metabolic rate
  • higher body temp
  • greater digestive capacity
  • lay fewer eggs
  • morphological changes in the heart, kidney, and spleen
33
Q

predictions of the evolutionary theory of aging

A

populations with lower rates of ecological mortality should evolve delayed

34
Q

antagonistic pleiotropy hypothesis

A

mutations conferring fitness benefits early in life & fitness costs later in life can be advantageous

35
Q

what is predicted by both theories of aging?

A
  • mutation accumulation hypothesis
  • antagonistic pleiotropy
36
Q

antagonistic pleiotropy

A

lower mortality means more individual will live long enough to experience late-life costs, so that natural selection on these mutations is stronger

37
Q

the antagonistic pleiotropy hypothesis for senescence

A

mutations conferring fitness benefits early in life & fitness costs late in life will be under positive selection when the benefits outweigh the costs

38
Q

mutation accumulation hypothesis

A
  • lower mortality means more individuals will live long enough to experience the deleterious effects of late-life
  • this increases the effectiveness of natural selection & holds deleterious alleles in mutation/selection balance at lower frequency
39
Q

antagonistic pleiotropy in the Virginia Possum

A
  • on an island = lower mortality
  • on the mainland = higher mortality
40
Q

connective tissue physiology

A
  • collagen fibers from cross links between protein molecules as we age, making out tendons stiffer
  • the amount of cross-linking can be measured by how hard it is to break the collagen fibers in tendons
41
Q

how many offspring in brown kiwi?

A
  • females weigh 6 lbs, lay a 1 lb egg
  • 1 large eggs
42
Q

connective tissue senescence

A

collagen fibers in the tail take longer to break in older individuals, but it is worse on the mainland

43
Q

how many offspring in sea urchins?

A
  • females take a few years to get to reproductive age
  • lay 100,000-20,000 tiny eggs
44
Q

fundamental trade-off between size & number of offspring

A

more offspring = smaller size
less offspring = large size

45
Q

parental fitness

A

number of offspring times expected survival

46
Q

study on Chinook Salmon

A
  • a * b = c
  • the optimal egg size in the hatchery is smaller than in nature & egg mass has evolved a smaller size in the hatchery
  • rivers that receive lots of hatchery fry have evolved smaller eggs as a consequence of gene flow from the hatchery fish
47
Q

Lack’s (1947) hypothesis

A

natural selection will favor the clutch size that maximizes the number of surviving offspring

48
Q

how does clutch size affect the probability of survival?

A

larger clutch size, smaller probability of survival

49
Q

Collard Flycatchers in Sweden

A
  • daughters from larger clutches have smaller clutches
  • trade-off between quantity & quality
  • the optimal clutch smaller size than the size that maximizes hatchling survival for any one year

Principals of Evolution (18 decks)

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