Question 1

This figure shows a metapopulation for the California spotted owl. Describe two ways in which this real metapopulation differs from the assumptions of the basic model of metapopulation dynamics, = (1 − e/c).

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This figure shows a metapopulation for...

Question 2

Riverview has 200 individuals, Oak Park has 600 individuals, and Mountainside has 50 individuals. Rank the populations in order from the most likely to go extinct to the least likely. Explain your reasoning.

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Question 3

When immigrants supplement a declining subpopulation, they prevent the subpopulation from going extinct. This phenomenon is known as

Accepted Answer

The rescue effect occurs when immigrants from neighboring populations prevent a declining subpopulation from going extinct. Option A (metapopulation) refers to a group of spatially separated populations of the same species that interact with one another. Option C (demographic stochasticity) refers to the random fluctuations in birth rates, death rates, and sex ratios that occur even in large populations. Option D (habitat fragmentation) refers to the breaking up of a large habitat into smaller, isolated fragments, which can lead to decreased genetic diversity and increased inbreeding.

Question 4

Which is an example of a metapopulation?
I. Insects live in isolated patches of forest surrounded by agriculture. Sometimes the population in a patch goes extinct, but eventually the insects recolonize that patch.
II. A species of bird is found in Canada during the summer. In the fall, the species migrates to the Caribbean and spends the winter there. In the spring it returns to Canada.
III. A species of fish lives in a fast-flowing cold river. A dam is constructed on the river, causing the fish to go extinct because of warmer water.

Accepted Answer

Metapopulations consist of separate populations that are connected by the movement of individuals between them, allowing for recolonization of habitats where populations may have gone extinct. Option I describes this scenario accurately, with insects living in isolated patches and recolonizing extinct patches, fitting the definition of a metapopulation. Options II and III do not describe metapopulations; II describes seasonal migration, and III describes extinction due to habitat change, neither of which involve the metapopulation concept of separate, interacting populations.

Question 5

Human activity can affect metapopulations. In the basic model of metapopulation dynamics, if humans improve the quality (and thus carrying capacity) of subpopulations, the probability of _____ and the proportion of occupied patches _____.

Accepted Answer

If the quality of subpopulations is improved, the carrying capacity increases, which in turn decreases the probability of extinction. As a result, the proportion of occupied patches also increases, as the improved quality and carrying capacity allow more subpopulations to persist.

Question 6

Based on the predictions of metapopulation biology, which scenario can be expected to exhibit the largest fraction of occupied habitat patches?

Accepted Answer

According to metapopulation biology, large patches close to one another are expected to exhibit the largest fraction of occupied habitat patches because they allow for greater dispersal and gene flow between patches, reducing the risk of patch extinction and promoting the colonization of empty patches. This is known as the rescue effect, which is more likely to occur in larger and more connected patches, allowing species to persist in the face of environmental disturbances. Small patches isolated from one another are expected to exhibit the lowest fraction of occupied habitat patches due to high extinction rates and limited colonization opportunities.

Question 7

Human activity can affect metapopulations. Under the basic model of metapopulation dynamics, when humans make it easier for individuals to travel between patches, the probability of _____ and the proportion of occupied patches _____.

Accepted Answer

When humans facilitate movement between patches, colonization increases as individuals can more easily move to and establish in new patches, leading to an increase in the proportion of occupied patches.

Question 8

A species of frog is found separated into many subpopulations living in ponds that are surrounded by agricultural fields. Sometimes one frog subpopulation goes extinct because of disease or environmental stochasticity. Frogs from other subpopulations will occasionally move across fields to recolonize ponds where subpopulations have gone extinct. This is an example of

Accepted Answer

This scenario describes a metapopulation, which is a population of subpopulations that are connected by occasional movement of individuals between them. The extinction and recolonization events illustrate the dynamics of a metapopulation.

Question 9

Which contributed to the decline and extinction of black-footed ferrets?
I. Habitat destruction reduced carrying capacity of ferrets.
II. Lethal diseases like canine distemper killed many ferrets.
III. Increasingly fragmented ferret populations were more likely to go extinct.

Accepted Answer

All three factors contributed to the decline and extinction of black-footed ferrets. Habitat destruction has reduced the carrying capacity of ferrets, making it harder for them to find food and shelter. Lethal diseases like canine distemper have killed many ferrets directly or weakened their immune systems, making them more susceptible to other infections. Increasingly fragmented ferret populations were more likely to go extinct because they had fewer opportunities to mate, find new habitats, and avoid genetic drift. Therefore, it's necessary to address all three factors to conserve black-footed ferrets successfully.

Question 10

Define the three components of the basic model of metapopulation dynamics, = (1 − e/c). Explain one way conservation biologists can affect each of the variables e and c to protect a species.

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Question 11

Under the basic model of metapopulation dynamics, when the extinction rate is equal to the colonization rate, we predict that the proportion of patches occupied ( ) will equal

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Question 12

Grasslands used to be spread across large portions of North America. However, human land use has separated formerly large, continuous grassland into many smaller isolated patches. This is an example of

Accepted Answer

Habitat fragmentation is the process by which large, contiguous habitats are broken up into smaller, isolated patches due to human land use. This can lead to negative impacts on wildlife populations, as they may be unable to access necessary resources or move between habitats.

Question 13

There are two key predictions about how extinction probability and colonization probability affect metapopulation dynamics. List these predictions and explain how they are illustrated by this figure.

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There are two key predictions about...

Question 14

A group of subpopulations has independent population dynamics over space. This is an example of

Accepted Answer

This scenario describes a metapopulation, where different subpopulations have their own independent dynamics but are connected by occasional migration and colonization events. Habitat fragmentation would imply a loss of connectivity between subpopulations, which is not mentioned here. The rescue effect and environmental stochasticity refer to specific mechanisms that can affect metapopulations, but they do not describe the basic structure of a metapopulation.

Question 15

Which is an example of the rescue effect?
I. A small population of birds maintains a stable population size near carrying capacity.
II. A population of mice in a low-quality habitat persists because of immigration from high-quality habitats.
III. Habitat destruction reduces the quality of an environment and causes a population of lizards to decline every year until they go extinct.

Accepted Answer

The rescue effect describes the situation in which a declining population is saved from extinction due to immigration from another population. Option II describes a population that persists because of the influx of individuals from a more favorable habitat, which is an example of the rescue effect. Options I and III do not involve immigration from another population and do not fit the definition of the rescue effect.

Question 16

A species of grass is affected by the amount of rainfall in the spring. In years of high rain, the grass survives better than in years of low rain. This is an example of

Accepted Answer

Environmental stochasticity refers to random variation in environmental factors, such as rainfall, that can affect population dynamics. The grass species being affected by the amount of rainfall in the spring is an example of environmental stochasticity. Demographic stochasticity refers to random events in individual survival and reproduction, damped oscillations refer to fluctuations in population size that dampen over time, and population cycles refer to predictable, cyclical fluctuations in population size.

Question 17

Which correctly describes metapopulations?
I. They can arise from habitat fragmentation.
II. The frequency of occupied habitats is due to the balance of extinction and colonization.
III. The basic metapopulation model assumes that all patches are equal in quality.

Accepted Answer

Metapopulations are indeed characterized by all three aspects mentioned: (I) They can form as a result of habitat fragmentation, which divides a larger population into smaller, isolated groups. (II) The dynamics of metapopulations are influenced by the balance between the rates of local extinctions and the colonization of new habitats. (III) The basic metapopulation model, for simplicity, often assumes that all habitat patches are of equal quality, although in reality, this may not be the case.

Question 18

Metapopulations

Accepted Answer

Metapopulations occur when suitable habitat patches for a species are interspersed with unsuitable habitat, allowing for populations to exist in a patchy environment. This concept emphasizes the dynamics of species across fragmented landscapes, where migration, extinction, and colonization rates among the patches influence the overall population dynamics.

Question 19

Under the basic model of metapopulation dynamics, which of the following conditions is necessary to prevent the species from going extinct?

Accepted Answer

In the basic metapopulation model, it is necessary for the colonization rate to be greater than the extinction rate to prevent the species from going extinct. This means that there must be a consistent and sufficient level of dispersal and colonization of new patches to offset the loss of individuals and populations due to extinction in existing patches.

Question 20

Which of the following contributed to the success of conservation programs that reintroduced ferrets to the wild?

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Quiz 13: Population Dynamics Over Space and Time