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population ecology > weeks 5-9 > Flashcards

weeks 5-9 Flashcards

1
Q

What is a metapopulation generally?

Give another definition that describes how it functions.

A

Levins 1970:

a population of many local populations.

Assemblage of local populations that interact via dispersal of individuals among patches.

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2
Q

Why is the metapopulation concept important for understanding fragmented landscapes?

A

Assumes that suitable habitat patches are sometimes unoccupied, so dispersal between patches can help metapopulation persist even if some patches go extinct.

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3
Q

In Levins’s model of a metapopulation:

  1. When is the rate of change of occupied patches maximized?
  2. When is the metapopulation in equilibrium?
A
  1. When the proportion of occupied patches = 0.5
  2. When p = 1 - (e/c), where p is proportion of occupied patches, e is extinction rate and c is colonization rate.
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4
Q

What 3 major metopop characteristics does Levins’s model ignore?

A
  1. Distance between patches
  2. Patch size
  3. Habitat quality
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5
Q

What are 2 major improvements of Hanski’s Incidence Function Model over Levins’s metapop model?

A
  1. Considers patch area, which is important for extinction risk (small pops more vulnerable to demographic stochasticity).
  2. Considers patch isolation, which determines colonization rate.
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6
Q

What is considered the major problem with small patch size in metapopulation theory, and what are two others?

A

Major problem: more vulnerable to demographic stochasticity.

Others:

  1. May affect population density.
  2. May affect likelihood of recolonization.
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7
Q

What is the Rescue Effect?

A

Less isolated patches should be more likely to be recolonized if they go extinct, and less likely to go extinct in the first place because of high immigration rates.

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8
Q

What are Hanski’s 4 main conditions for a metapopulation?

A
  1. Local breeding pops occur in discrete patches.
  2. No local pop so large that it’s expected lifetime is much longer than the other local pops.
  3. Dynamics of local pops are asynchronous.
  4. Patches are close enough together that recolonization is possible.
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9
Q

What is a mainland-island system?

A

Group of local populations where one is much larger than all the others.

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10
Q

Why isn’t the rescue effect helping keep WNS populations in the NE U.S. from going extinct?

A

Don’t meet Hanski’s synchrony criterion for a metapop: all are being affected by the same thing at the same time.

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11
Q

What is dispersal?

A

One-way movement of individual beyond its home range.

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12
Q

How does breeding dispersal differ from natal dispersal?

A

Natal dispersal: movement of individual away from natal range to a place where it will reproduce.

Breeding dispersal: movement of adults between breeding attempts.

…male bats have high natal dispersal and low breeding dispersal (just move from one girl to the next in a cluster!).

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13
Q

What are 3 ultimate causes of dispersal?

A
  1. Inbreeding avoidance
  2. Competition for mates
  3. Competition for resources
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14
Q

What is Greenwood’s mating system hypothesis of sex-biased dispersal?

A

Predominant mating system for male birds: territory defense.

Predominant mating system for male mammals: defense of access to females.

So male birds establish a territory and defend it, while male mammals find females and defend them.

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15
Q

What is Jerry Wolff’s theory of sex-biased dispersal patterns?

A

Intramale competition is intense, so males tend to not stay dominant in one area for a long time. Thus, daughters don’t have to worry about mating with dad if they stay put, but do have to worry about mating with son, so son disperses.

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16
Q

What were Dan Simberloff’s 3 main criticisms of connectivity corridors?

A
  1. Spread of disease & invasive species
  2. Reservoirs for edge species
  3. Ecological sinks
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17
Q

Describe the large-scale analysis by Haddad, et al., that demonstrated the effectiveness of corridors.

A

Grassland patches separated by matrix of forest in South Carolina, some connected by corridors and others not.

Compared movement between connected and unconnected patches for several species of insects, mammals and plants. Found greater movement for most species (across all taxa)!

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18
Q

What are 4 potential alterations to landscapes that may help buffer from the effects of demographic stochasticity?

A
  1. Corridors
  2. Stepping Stones
  3. Increase patch size
  4. Make matrix more crossable (decrease effective distance).
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19
Q

What was Judy Stamps’s experiment that asserted that even territorial species exhibit conspecific attraction?

A

Set up two areas in the middle of a ring of (territorial) juvenile anolis lizard homesites.

Both had uniform distribution of resources, one had males already established, other did not.

Juvenile males settled nearer to established territory than in unestablished territory.

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20
Q

What are 3 potential explanations of conspecific attraction?

A
  1. Provides cues about habitat quality.
  2. Mating success.
  3. Predator protection.
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21
Q

What is habitat imprinting?

A

Tendency to choose habitats that are similar to natal habitat.

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22
Q

What is the Ideal Free Distribution?

A

Animals will space themselves so that fitness is equal everywhere, provided:

they can accurately assess habitat quality, and

can move freely between patches.

23
Q

Graph Ideal Free Distribution of two habitats.

A
24
Q

Graph a fitness isocline for 2 habitats of different quality: one with K = 100 and one with K = 50.

A
25
Q

Name 2 alternatives to the Ideal Free Distribution.

A
  1. Ideal Despotic Distribution (more competitive individuals monopolize better quality habitat)
  2. Ideal Preemptive Distribution (heterogeneity in habitat quality within a patch. Thows who arrive first take the best.)
26
Q

Describe the source-sink model.

A

Source habitat: b>d, e>i; net exporter of animals.

Sink habitat: b<d></d>

27
Q

Describe Pulliam’s Source-Sink Model.

A

Source habitat is density dep.

Limited # of breeding sites in source.

Sink has unlimited number of poor breeding sites.

When no availability at source site, animals inhabit sink site.

28
Q

What are the 5 top causes of extinction in vertebrates (in order)?

A
  1. Habitat alteration
  2. Exotic species
  3. Overharvest
  4. Pollution
  5. Disease
29
Q

Name 9 characteristics that make wildlife more prone to extinction.

A
  1. Habitat specialization
  2. Habitat overlaps with humans
  3. Sensitive to disturbance
  4. Limited dispersal ability
  5. Rare (low pop density, restricted geographic range)
  6. Low growth rate
  7. Large body size
  8. Harvestable
  9. High trophic level
    10.
30
Q

What are the 4 traits that explain the majority of the variation in extinction risk?

A
  1. High trophic level
  2. Low population density
  3. Slow life history
  4. Small geographic range
31
Q

What is latent extinction risk?

A

= Predicted risk - Current risk.

Species that currently are at high risk of extinction have a low latent extinction risk because we assume they’ll already be gone in the future!

32
Q

Which 3 general areas of the world have the highest latent extinction risk?

A
  1. Far north in N America & Asia.
  2. Malay peninsula / islands btw Asia & Australia
  3. Far south: Patagonian coast and Tasmania.
33
Q

What is PVA?

A

Population Viability Analysis:

Quantitative assessment of a pop’s risk of extinction or quasi-extinction.

34
Q

Name a few (up to 5) uses of PVA in wildlife management.

A
  1. Identifying key lifestages
  2. Determining required N for a reserve
  3. Determining N to release in introduction
  4. Setting harvest limits
  5. Deciding # of pop’s needed for regional persistence
35
Q

What are the 4 main types of PVA models?

A
  1. Deterministic single population models
  2. Stochastic single population model
  3. Metapopulation model
  4. Spatially-explicit Individual Based Model
36
Q

What are 5 common criticisms of PVA?

A
  1. Poor data quality
  2. Form of density dependence unknown
  3. Patterns of environmental stochasticity might not hold in future
  4. Canned programs with built-in assumptions
  5. Models not validated with field data
37
Q

What evidence do we have that PVA is useful?

A

Meta-analysis by Brooks, et al.

Used first half of data sets from PVA analyses done from long-term studies to conduct new PVA analyses

PVA from first half of data predicted end results of last half of data well. (all fell within bounds predicted by stochastic simulations).

38
Q

5 recommendations for careful use of PVA.

A
  1. Test models with independent field data and adjust.
  2. Evaluate relative rather than absolute rates of extinction.
  3. Don’t expect PVA to be accurate enough to give a single value like MVP.
  4. Include uncertainty analysis (i.e. How much does a change to any one assumption change the outcome?)
  5. Compare short-term vs long-term projections.
39
Q

What was Lande’s (1988) criticism of conservation genetics?

What was Spielman’s counter-point?

A

Demography usually has a bigger influence on extinction risk than genetic diversity.

Heterozygosity in threatened taxa was %35 lower than in non-threatened.

40
Q

Draw a diagram of the extinction vortex.

A
41
Q

What is interspecific competition?

A

Exploitation or interference

of a SHARED RESOURCE

between two or more species,

with a negative impact on at least one species.

42
Q

What is a niche?

A

Environmental factors that influence growth, survival and reproduction of a species.

43
Q

What’s the difference between a fundamental niche and a realized niche?

A

Fundamental niche is the ideal situation without competitors,

Realized niche is the actual situation due to presence of competitors.

44
Q

What is Gause’s competitive exclusion principle?

A

Ecologically similar species cannot coexist at equilibrium if they are using the same limited resource.

45
Q

Give 6 criteria for determining that interspecific competition is occurring, from least to most convincing.

A
  1. Observe patterns consistent with predictions.
  2. Species overlap in resource use.
  3. Intraspecific competition occurs.
  4. Resource use by one species reduced availability by other species.
  5. Alternative hypotheses not consistent with observed patterns.
46
Q

What are the Lotka-Volterra interspecific competition models?

A

…and also the reverse equation with α as the competition coefficient (couldn’t upload 2 images).

47
Q

When does Lotka-Volterra Competition model predict that two species will co-exist?

A

When intraspecific competition > interspecific competition.

48
Q

What are the equilibrium population densities for 2 pops under Lotka-Volterra competition model?

A
49
Q

Graph the isocline for species 1 in the Lotka-Volterra competition model.

A
50
Q

Graph the isocline for species 2 in the Lotka-Volterra competition model.

A
51
Q

Graph the outcome if species 1 outcompetes species 2 in a Lotka-Volterra model.

A
52
Q

Graph isoclines of two species in stable coexistence at equilibrium in a Lotka-Volterra model.

A
53
Q

What was John Wiens’s view on competition theory?

A

Resource limitation is rare, so competition isn’t nearly as important as environmental variation. Equilibrium in nature is basically a myth.

54
Q

What is Apparent Competition?

A

Process that negatively impacts two prey species that do not compete for resources, because they have the same natural enemy.

population ecology (3 decks)

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