Chapter 11

Which processes increase a population's size?

Births and immigration

Which of the following statements about territories and home ranges is FALSE?

Carnivores have smaller home ranges than similar-sized herbivores.

What are population dynamics?

Changes in populations through time.

Which of the following statements about density dependence is FALSE?

Density-dependent factors alone cannot limit population growth.

Which of the following statements about density-independent growth is true?

Density-independent growth is also known as exponential growth.

Which factor does not affect a habitat's carrying capacity?

Genetic variation in the population

Which of the following statements about intraspecific competition is FALSE?

Growth rates of plants are only slightly influenced by intraspecific competition but are greatly depressed by the presence of interspecific competition.

Which of the following statements about a population experiencing logistic growth is true?

If N is greater than K, the population will shrink.

The average age of childbearing in country A is 26, whereas the average age in country B is 30. In each country, the average number of offspring per woman is 3. Which of the following statements about the population growth rate in each country must be true?

It is not possible to compare the population growth rates of countries A and B.

Under the logistic growth model, the rate of population growth is highest when

N = K/2

Which of the following statements is FALSE? Plants are territorial, just like animals. Uniform distributions are often an indication that competition exists among plant populations. Shading by large plants can limit the establishment of other plants. Trees sometimes occupy space for a long time and prevent the establishment of other species by establishing a zone of resource depletion (sunlight, water or nutrients). Plants capture space and exclude other individuals from it.

Plants are territorial, just like animals.

Which of the following statements about age pyramids is true?

Predictions of a population's future take into account such factors as increasing survivorship and fecundity levels that remain the same.

In 1970, the average age of childbearing was 28, and the average number of offspring per woman was 3 in a certain country. In 1980, the average age of childbearing was still 28, but the average number of offspring per woman was 2 in that country. If the death rate in the country remained constant during those years, how did the population growth rate change from 1970 to 1980?

The population growth rate decreased.

The logistic model effectively has two components: the original exponential term (rN) and a second term (1 − N/K). What is the function of the second term in this model?

The term 1 − N/K functions to reduce population growth as the population size approaches the carrying capacity.

T or F: True or false? The growth rate of a certain population increases very quickly for a time and then levels off to zero. The most likely reason that the growth rate leveled off to zero is that the population reached the carrying capacity of that environment.

True

True or false? Factors that determine the per capita rate of increase of a population include the age of breeding and the number of offspring produced each year.

True

Under which of the following conditions would a population most likely experience exponential growth?

Young populations with few individuals.

What information is needed in order to determine the minimum dynamic area (MDA) for a species?

an estimate of minimum viable population and knowledge of the area requirement per individual of a species

At K, what is the relationship between b and d?

b = d

Which of the following organisms would be most likely to present evidence of self-thinning?

barnacle

As population density increases in harp seals (Phoca groenlandica), females

begin reproduction at a later age.

As population size (N) increases, the per capita

birthrate decreases and death rate increases.

Among mammals, the home range is usually larger for

carnivorous species than for herbivorous species of the same body size.

In logistic growth, the point at which population growth ceases is referred to as the

carrying capacity

The __________ is the maximum population size that can be supported by normal environmental conditions.

carrying capacity

You see two squirrels fighting over a food resource. This most likely represents

contest competition

One way to reduce density dependence is

dispersal

T or F: As the density of a population increases, dispersal usually decreases.

false

T or F: High-density conditions caused no noticeable change in the behavior of experimental wood frog (Rana sylvatica) tadpoles.

false

T or F: Scramble competition results in some individuals in the population getting more resources than others.

false

T or F: Social organization occurs only among invertebrate animals such as ants, bees, and termites.

false

T or F: The home range of an animal is always defended.

false

T or F: When a given area is saturated with territories, excluded individuals who lack a territory soon die of starvation.

false

As the density of a population increases, the

individual growth rate decreases.

Density-independent population regulation

is usually catastrophic

One way to reduce density dependence is

is usually closely related to the alpha male.

Social dominance can serve to

limit population size

The carrying capacity refers to the

maximum sustainable population size for the prevailing environment.

The fewest number of individuals necessary to ensure the long term survival of a population is known as the

minimum viable population

The individuals that disperse as a response to high population density are

mostly the younger members of the population.

According to the logistic model of population growth, the maximum rate of growth __________.

occurs at intermediate population densities

What might be an unforeseen outcome of planting soybean plants at high densities in a field?

reduced seed production per plant

Plants can preempt both space and _____

resources

On a graph of population size versus time for a population undergoing logistic growth, the line showing the population's size is __________.

sigmoidal

An area defended by an animal is known as its __________.

territory

The decline in either reproduction or survival under conditions of low population density is known as __________.

the Allee effect

When individuals in a small population have difficulty finding a mate, this is referred to as

the Allee effect

When experimental plants (e.g., Atriplex prostrata) were grown at high densities,

the proportion of resources allocated to leaf production increased.

T or F: Fire is an example of a density-independent factor that affects the size of a population.

true

T or F: For a given body size, the home range of carnivores is greater than that of herbivores.

true

T or F: No population continues to grow in size indefinitely.

true

T or F: Plants can capture and defend space.

true

T or F: Territorial behavior includes some form of advertisement, threat, and combat.

true

T or F: The carrying capacity (K) of a population can vary depending on the supply of resources.

true

T or F: The influence of density-independent factors on populations is generally less predictable than the influence of density-dependent factors.

true

Which of the following is a density-independent factor? availability of mates food availability shelter availability weather event

weather event

Which equation represents the logistic growth rate of a population?

ΔN/Δt =rmaxN((K−N)/K)