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population ecology > weeks 10-14 > Flashcards

weeks 10-14 Flashcards

1
Q

What is predation?

A

Consumption of one organism by another in which the prey organism is alive and the predator organism attacks it.

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2
Q

What is the HSL or Green World Hypothesis?

A

Factor that limits growth depends on trophic level.

Producers, carnivores and decomposers are density-dependent.

Herbivores are limited by predators.

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3
Q

What is a trophic cascade?

A

Interactions between trophic levels

that result in inverse patterns in abundance or biomass

across more than one trophic level.

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4
Q

Describe the hypothesized sea otter trophic cascade that is used to explain kelp population declines.

A
  1. Over-fishing has caused seal decline.
  2. Seal decline has caused orcas to prey on sea otters.
  3. Decline in sea otters has led to sea urchin pop explosion.
  4. High sea urchin pop sizes have led to kelp declines.
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5
Q

What are the Lotka-Volterra predator and prey (victim) equations?

A
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6
Q

From the Lotka-Volterra predator-prey equations, derive the equation that determines the number of predators needed to keep victims at zero growth.

A
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7
Q

From the Lotka-Volterra predator-prey equations, derive the equation that determines the number of victims needed to keep predators at zero growth.

A
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8
Q

Graph the victim isocline from the Lotka-Volterra predator-prey models.

A
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9
Q

Graph the predator isocline from the Lotka-Volterra predator-prey models.

A
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10
Q

Graph predator-prey dynamics based on predator and prey isoclines from the LV models.

A
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11
Q

Graph predicted growth of predator and prey populations over time according to LV models.

A
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12
Q

List 5 unrealistic assumptions of the LV predator-prey models.

A
  1. Prey pop only limited by predation.
  2. Predator only eats one type of prey.
  3. Predators can eat unlimited amts instantaneously.
  4. Victims have no refuge from predators.
  5. No dispersal, age structure, time lags.
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13
Q

What are two ways to stabilize predator-prey interactions in LV models?

A
  1. Make prey population density-dependent.
  2. Make predator population density-dependent.
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14
Q

What is compensatory mortality and what is additive mortality?

A

Compensatory: only the weak/sick/old harvested, so doesn’t limit prey numbers.

Additive: each prey harvested reduces pop size by 1 from what it would have been otherwise.

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15
Q

What is “numerical response”?

A

Relationship between density of predator pop and prey abundance.

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16
Q

What is “functional response”?

A

Relationship between consumption rate of predator and prey abundance.

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17
Q

What is hyperpredation?

A

A form of apparent competition, where an introduced prey species enables a shared predator of a native species to increase in population size.

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18
Q

What is intraguild predation?

A

Potentially competing species that also have a predator-prey relationship.

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19
Q

How does “predation rate” integrate numerical and functional responses?

A

Predation regulates prey populations at low prey densities.

Intraspecific competition of prey species and food regulation of prey species limit prey populations at medium and high densities.

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20
Q

Who wrote the classic paper on population cycles titled “Periodic fluctuations in the number of animals: their causes and effects”, and when was it published?

A

Charles Elton 1924

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21
Q

What was the Chitty Hypothesis?

A

Vole and lemming populations consist of docile and aggressive personalities.

At high density, selection favors aggressives, which are competitve survivors but poor breeders, causing pop to decline.

At low density, selection favors doclies, which are good breeders, causing pop to grow.

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22
Q

What is the Nutrient Recovery Hypothesis?

A

When herbivore pop’s are low, increased standing vegetation decomposes to fertilize soil, causing more vegetation to grow.

Increased vegetation leads to increase herbivore survival and repro, which intensifies grazing.

Depletion of vegetatoin causes herbivore pop’s to decline.

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23
Q

What is the specialist predator hypothesis?

A

Voles have 3 predators:

  1. generalist predators (that usually eat something else)
  2. resident specialists (whose populations are tied to voles with a time lag)
  3. nomadic specialists (avian - that move across large areas looking for voles)

1 and 3 should have stabilizing effect on population sizes, while 2 drives cyclicity.

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24
Q

What is an “index” in terms of abundance and density?

A

A count of animals (or signs of) that hopefully gives a sense of relative number or density at a site.

NOT an estimate of N or density!

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25
Q

What is a closed-population model?

When is it used?

A

Assumes that N is not changing over time (no BIDE).

Used to estimate population size.

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26
Q

What is an open-population model?

What is it used for?

What is it not so good for, and why?

A

Pop model that allows for BIDE.

Most useful for estimating S.

Not so good for estimating N, because estimates of N in an open pop tend to be biased.

27
Q

What is the Lincoln-Peterson estimator?

What does it assume?

A

N-hat = (n1n2)/m2

where n1 = number banded on first trap-night,

n2 = number captured on second trap-night,

m2 = number of marked individuals captured on second trap-night.

Assumes no BIDE (closed pop).

28
Q

Describe the 4 following multiple-recapture models:

Mo, Mt, Mb, Mh

A

Mo : equal probability of capturing every individual on every occasion.

Mt : all individuals have equal probability of being captured, but not all occasions.

Mb : probability of 1st capture different from probability of recapture(s). Does not vary between individuals.

Mh : individuals have different probabilities of capture (due to age, gender, etc.), but occasions have equal capture porbability.

29
Q

In recapture models, what is… ?

p2

φ2

A

p2 = probability of recapture on occasion 2

φ2 = probability of survival from occasion 2 to occasion 3

30
Q

What is the probability of encounter history 111?

(Express in terms of p and φ, and in English)

A

φ1p2φ2p3

The probability of surviving from time 1 to time 2 AND the probability of being recaptured on time 2 AND the probability of surviving from time 2 to time 3 AND the probability of being recaptured on time 3

31
Q

What is the probability of encounter history 110?

(Express in terms of p and φ, and in English)

A

The probability that:

survived to t2 AND died btw t2-t3 OR survived to t3 AND wasn’t recapped in t3.

32
Q

What is the probability of encounter history 101?

(Express in terms of p and φ, and in English)

A

= φ1(1-p2)φ2p3

Probability that: survived from t1-t2 AND was not recapped in t2 AND the probability that survived t2-t3

33
Q

What can you estimate with a Jolly-Seber model?

Which estimates will likely be biased?

A

Year-specific estimates of:

Apparent survival (φ=S+e)

Capture probability (p)

Population size (N)

New ind’s in pop (B = b+i)

N and B are often biased.

34
Q

Which 2 pairs of parameters can’t be distinguised in a Jolly-Seber model?

A

survival can’t be separated from emigration, and recruitment can’t be separated from immigration.

35
Q

What are 2 assumptions of the Jolly-Seber model?

A

Animals are randomly sampled from the population.

Marked and unmarked are equally likely to be recaptured.

36
Q

How does Jolly-Seber model differ from Lincoln-Petersen model?

A

Lincoln-Peterson is only 2 capture events, while JS is multiple.

LP assumes a closed population, while JS does not.

37
Q

How is the Jolly-Seber model different from the Cormack-Jolly-Seber model?

A

JS estimates N, B, φ and p.

CJS only estimates φ and p.

CJS does not assume that marked and unmarked are equally likely to be recaptured.

38
Q

What do these notations mean for CJS models?

A
39
Q

What is the Robust Design?

A

Uses a closed capture model within a year to estimate N.

Uses a CJS model between years to estimate φ between years.

40
Q

Dead-recovery design is usually used to estimate what?

A

Survival rates for exploited pops

41
Q

What are known-fate models?

A

Estimate survival from radio-tagged individuals or from nest survival.

42
Q

What is censoring in known-fate models?

A

Uncertainty of fates of some ind’s due to radiotransmitter failure or dispersal beyond the detection range.

43
Q

What does distance sampling model?

A

Models how detectability drops off with increasing distance from line to estimate number of individuals corrected for detection probability.

44
Q

What is the general design of distance sampling studies?

A

Usually line-transects (sometimes point counts).

Record observations of target species and their distances from the line.

45
Q

4 assumptions of distance sampling.

A
  1. all animals on line are detected.
  2. detection of individuals is independent.
  3. each animal counted only once.
  4. distacnes measured accurately.
46
Q

What are 4 methods for measuring abundance?

A
  1. Census (complete count)
  2. Mark-recap for closed pop (Lincoln-Petersen)
  3. Mark-recap for open pop (Jolly-Seber)
  4. Distance sampling
47
Q

What are 3 methods for estimating survival?

A
  1. Mark-recap for open pop (CJS)
  2. Dead recovery
  3. Known fate models
48
Q

What is the method for getting estimates of both abundance and survival?

A

Mark-recap with robust design

49
Q

What’s a major problem with using mark-recapture to study dispersal distances?

A

Only detect those within study area, so systematically underestimate dispersal.

50
Q

What is a partial correction for bias in mark-recapture studies of dispersal?

Why is it only a partial correction?

A

Correct observed distributions for distance-specific detection probabilities.

Only corrects for distances < maximum detection distance.

51
Q

What is a mark-recapture multistate/multistrata design?

A

Estimates transition probabilities between pairs of sites

when animals move between geographic areas

that differ in survival and recapture probabilities.

52
Q

What’s a big problem with multistate/multistrata designs?

A

They have so many parameters that they are extremely data hungry.

53
Q

What’s a much less biased method (relative to mark-recapture) to determine dispersal distances?

But….

A

Radio telemetry

…but movements beyond search zone still go undetected.

54
Q

What does a high Fst value tell you about dispersal between populations?

A

High Fst indicates low gene flow, interpreted as high isolation by distance. Individuals in these populations are dispersing very far.

55
Q

If you don’t have dispersal data for your species, what characteristic can you use as a proxy for dispersal?

For which species does this approach work best?

A

Body mass

mammals > birds

carnivores > herbivores

56
Q

If you don’t know dispersal distance for a species, what other spatial information can you use as a proxy?

A

Home range size

57
Q

What really important factor is ignored when using proxies for dispersal to estimate dispersal differences?

A

Interspecies dispersal differences due to demography, fragmentation, matrix differences, etc.

58
Q

What is a flagship species?

A

Species selected by an organization to attract public attention and funding.

59
Q

Describe 2 problems with using flagship species to garner public support for conservation research.

A
  1. What if flagship “sinks”? (Simberloff)
  2. What’s best for flagship conservation might not be what’s most effective for other species / ecosystem.
60
Q

What is an umbrella species?

A

Species whose conservation provides protection from many co-occurring species.

61
Q

What is the umbrella index?

A

System of choosing umbrella species based on 3 criteria:

  1. tendency to co-occur with other species
  2. degree of ubiquity
  3. sensitivity to human disturbance
62
Q

What is an indicator species?

A

Organism whose population conditions are used as an index of quality of the environment, or other species that are difficult to study.

63
Q

What is a keystone species?

A

A species that is “really important” in an ecosystem.

64
Q

Name 3 specific types of keystone species.

A
  1. Keystone predators (top-down trophic control)
  2. Keystone mutualists (pollinators & seed dispersers)
  3. Keystone modifiers (ecological engineers, like beavers)

population ecology (3 decks)

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