weeks 5-9

Question 1

What is a metapopulation generally?

Give another definition that describes how it functions.

Answer 1

Levins 1970:

a population of many local populations.

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

Question 2

Why is the metapopulation concept important for understanding fragmented landscapes?

Answer 2

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

Question 3

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?

Answer 3

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.

Question 4

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

Answer 4

1. Distance between patches
2. Patch size
3. Habitat quality

Question 5

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

Answer 5

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.

Question 6

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

Answer 6

Major problem: more vulnerable to demographic stochasticity.

Others:

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

Question 7

What is the Rescue Effect?

Answer 7

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.

Question 8

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

Answer 8

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.

Question 9

What is a mainland-island system?

Answer 9

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

Question 10

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

Answer 10

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

Question 11

What is dispersal?

Answer 11

One-way movement of individual beyond its home range.

Question 12

How does breeding dispersal differ from natal dispersal?

Answer 12

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!).

Question 13

What are 3 ultimate causes of dispersal?

Answer 13

1. Inbreeding avoidance
2. Competition for mates
3. Competition for resources

Question 14

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

Answer 14

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.

Question 15

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

Answer 15

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.

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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)!

Question 18

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

Answer 18

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

Question 19

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

Answer 19

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.

Question 20

What are 3 potential explanations of conspecific attraction?

Answer 20

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

Question 21

What is habitat imprinting?

Answer 21

Tendency to choose habitats that are similar to natal habitat.

Question 22

What is the Ideal Free Distribution?

Answer 22

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

they can accurately assess habitat quality, and

can move freely between patches.

Question 23

Graph Ideal Free Distribution of two habitats.

Answer 23

Question 24

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

Answer 24

Question 25

Name 2 alternatives to the Ideal Free Distribution.

Answer 25

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.)

Question 26

Describe the source-sink model.

Answer 26

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

Question 27

Describe Pulliam's Source-Sink Model.

Answer 27

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.

Question 28

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

Answer 28

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

Question 29

Name 9 characteristics that make wildlife more prone to extinction.

Answer 29

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.

Question 30

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

Answer 30

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

Question 31

What is latent extinction risk?

Answer 31

= 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!

Question 32

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

Answer 32

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

Question 33

What is PVA?

Answer 33

Population Viability Analysis: Quantitative assessment of a pop's risk of extinction or quasi-extinction.

Question 34

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

Answer 34

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

Question 35

What are the 4 main types of PVA models?

Answer 35

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

Question 36

What are 5 common criticisms of PVA?

Answer 36

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

Question 37

What evidence do we have that PVA is useful?

Answer 37

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).

Question 38

5 recommendations for careful use of PVA.

Answer 38

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.

Question 39

What was Lande's (1988) criticism of conservation genetics? What was Spielman's counter-point?

Answer 39

Demography usually has a bigger influence on extinction risk than genetic diversity. Heterozygosity in threatened taxa was %35 lower than in non-threatened.

Question 40

Draw a diagram of the extinction vortex.

Answer 40

Question 41

What is interspecific competition?

Answer 41

Exploitation or interference of a SHARED RESOURCE between two or more species, with a negative impact on at least one species.

Question 42

What is a niche?

Answer 42

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

Question 43

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

Answer 43

Fundamental niche is the ideal situation without competitors, Realized niche is the actual situation due to presence of competitors.

Question 44

What is Gause's competitive exclusion principle?

Answer 44

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

Question 45

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

Answer 45

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.

Question 46

What are the Lotka-Volterra interspecific competition models?

Answer 46

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

Question 47

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

Answer 47

When intraspecific competition \> interspecific competition.

Question 48

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

Answer 48

Question 49

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

Answer 49

Question 50

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

Answer 50

Question 51

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

Answer 51

Question 52

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

Answer 52

Question 53

What was John Wiens's view on competition theory?

Answer 53

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

Question 54

What is Apparent Competition?

Answer 54

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