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Chapter 53

"A population is correctly defined as having which of the following characteristics? I. Inhabiting the same general area. II. Individuals belonging to the same species. III. Possessing a constant and uniform density and dispersion.

I only

III only

I and II only

II and III only

I, II, and III

An ecologist recorded 12 white - tailed deer, Odocoileus virginianus, per square mile in one woodlot and 20 per square mile on another woodlot. What was the ecologist comparing?

Density

Dispersion

Carrying capacity

Quadrats

Range

To measure the population density of monarch butterflies occupying a particular park, 100 butterflies are captured, marked with a small dot on a wing, and then released. The next day, another 100 butterflies are captured, including the recapture of 20 marked butterflies. One would estimate the population to be

200

500

1000

10000

900000

The most common kind of dispersion in nature is

Clumped.

Random.

Uniform.

Indeterminate.

Dispersive.

Uniform spacing patterns in plants such as the creosote bush are most often associated with

Chance.

Patterns of high humidity.

The random distribution of seeds.

Competitive interactions among individuals in the population.

Th e concentration of nutrients within the populationʹs range.

Which of the following groups would be most likely to exhibit uniform dispersion?

Red squirrels, who actively defend territories

Cattails, which grow primarily at edges of lakes and strea ms

Dwarf mistletoes, which parasitize particular species of forest tree

Moths in a city at night

Lake trout, which seek out deep water

In order to construct a reproductive table for a sexual species, you need to

Assess sperm viability.

K eep track of all of the offspring of a cohort.

Keep track of the females in a cohort.

Keep track of all of the offspring of the females in a cohort.

Keep track of the ratio of deaths to births in a cohort.

Which of the following examples would most accurately measure the density of the population being studied?

Counting the number of prairie dog burrows per hectare

Counting the number of times a 1 kilometer transect is intersected by tracks of red squirrels after a snowfall

Counting th e number of coyote droppings per hectare

Multiplying the number of moss plants counted in 10, 1m2 quadrats by 100 to determine the density per kilometer2.

Counting the number of zebras from airplane census observations.

To measure the population of lake trout in a 250 hectare lake, 200 individuals were netted and marked with a fin clip, and then returned to the lake. The next week, the lake is netted again, and out of the 200 lake trout that are caught, 50 have fin cl ips. Using the capture - recapture estimate, the lake trout population size could be closest to which of the following?

200

250

400

800

40000

"Which of the following assumptions have to be made regarding the capture - recapture estimate of population size? I. Marked and unmarked individuals have the same probability of being trapped. II. The marked individuals have thoroughly mixed with population after being marked. III. No individuals have entered or left the population by immigration or e migration, and no individuals have been added by birth or eliminated by death during the course of the estimate.

I only

II only

I and II only

II and III only

I, II, and III

Natural selection has led to the evolution of diverse natural hi story strategies, which have in common

Many offspring per reproductive episode.

Limitation only by density - independent limiting factors.

Adaptation to stable environments.

Maximum lifetime reproductive success.

Relatively large offspring.

Natural selection involves energetic trade - offs between

Choosing how many offspring to produce over the course of a lifetime and how long to live.

Producing large numbers of gametes when employing internal fertilization versus fewer numbers of game tes when employing external fertilization.

The emigration of individuals when they are no longer reproductively capable or committing suicide.

Increasing the number of individuals produced during each reproductive episode with a corresponding decrease in parental care.

High survival rates of offspring and the cost of parental care.

The three basic variables that make up the life history of an organism are

Life expectancy, birth rate, and death rate.

Number of reproductive females I n the population, age structure of the population, and life expectancy.

Age when reproduction begins, how often reproduction occurs, and how many offspring are produced per reproductive episode.

How often reproduction occurs, life expectancy of femal es in the population, and number of offspring per reproductive episode.

The number of reproductive females in the population, how often reproduction occurs, and death rate.

A population of ground squirrels has an annual per capita birth rate of 0.06 and an annual per capita death rate of 0.02. Estimate the number of individuals added to (or lost from) a population of 1,000 individuals in one year.

120 individuals added

40 individuals added

20 individuals added

400 individuals added

20 individuals lost

A small population of white - footed mice has the same intrinsic rate of increase ( r ) as a large population. If everything else is equal,

The large population will add more individuals per unit time.

The small population will add m ore individuals per unit time.

The two populations will add equal numbers of individuals per unit time.

The J - shaped growth curves will look identical.

The growth trajectories of the two populations will proceed in opposite directions.

Imagine that you are managing a large ranch. You know from historical accounts that wild sheep used to live there, but they have been extirpated. You decide to reintroduce them. After doing some research to determine what might be an appropriately sized founding population, you do so. You then watch the population increase for several generations, and graph the number of individuals (vertical axis) against the number of generations (horizontal axis). The graph will appear as

A diagonal line, getting higher with each generation.

An ʺS,ʺ increasing with each generation.

An upside - down ʺU.ʺ

A ʺJ,ʺ increasing with each generation.

In the logistic equation dN/dt = rN (K - N)/K , r is a measure of the populationʹs intrinsic rate of increase. It is determined by which of the following?

Birth rate and death rates

Dispersion

Density

Carrying capacity

Life history

In 2005, the United States had a population of approximately 295,000,000 people. If the birth rate was 13 births for every 1,000 peo ple, approximately how many births occurred in the United States in 2005?

3800

38000

380000

3800000

38000000

Exponential growth of a population is represented by dN/dt =

RN/K

RN (K + N)

RN (K - N)/K

RN (N - K)/K

Logistic growth of a population is represented by dN/dt =

RN/K

RN (K + N)

RN (K - N)/K

RN (N - K)/K

As N approaches K for a certain population, which of the following is predicted by the logistic equation?

The growth rate will not change.

The growth rate will approach zero.

The population will show an Allee effect.

The population will increase exponentially.

The carrying capacity of the environment will increase.

Often the growth cycle of one population has an effect on the cycle of another. As moose populations increase, wolf populations also increase. Thus, if we are considering the logistic equation for the wolf population, dN/dt = rN (K - N)/K , which of the factors accounts for the effect on the moose populati on?

Which of the following might be expected in the logistic model of population growth?

As N approaches K , b increases.

As N approaches K , r increases.

As N approaches K , d increases.

Both A and B are true.

B oth B and C are true.

In models of sigmoidal (logistic) population growth,

Population growth rate slows dramatically as N approaches K .

New individuals are added to the population most rapidly at the beginning of the populationʹs growth.

Only density - dependent factors affect the rate of population growth.

Only density - independent factors affect the rate of population growth.

Carrying capacity is never reached.

Which of the following is the pattern of spacing for individuals within the boundaries of the population?

Cohort

Dispersion

Allee effect

Iteroparous

Semelparous

Pacific salmon or annual plants illustrate which of the following?

Cohort

Dispersion

Allee effect

Iteroparous

Semelparous

Which of the following describes having more than one reproductive episode during a lifetime?

Cohort

Dispersion

Allee effect

Iteroparous

Semelparous

Which of the following is true ?

K - selection operates in populations where populations flu ctuate well below the carrying capacity.

R - selection occurs in populations whose densities are very near the carrying capacity.

Different populations of the same species will be consistently r - or K - selected.

R - and K - selection are two extremes of a range of life history strategies.

The life history traits favored by selection are most likely to vary with

Fluctuations in K .

The shape of the J curve.

The maximum size of a population.

Population density.

Population dispersion.

In which of the following habitats would you expect to find the largest number of K - selected individuals?

A recently abandoned agricultural field in Ohio

The sand dune communities of south Lake Michigan

The flora and fauna of a coral reef in the Caribbean

South Florida after a hurricane

A newly emergent volcanic island

Which of the following characterizes relatively K - selected populations?

Offspring with good chances of survival

Many offspring per reproductive episode

Small offspring

A high intrinsic rate of increase

Early parental reproduction

Your friend comes to you with a problem. It seems his shrimp boats arenʹt catch ing nearly as much shrimp as they used to. He canʹt understand why because originally he caught all the shrimp he could handle. Each year he added a new boat, and for a long time each boat caught tons of shrimp. As he added more boats, there came a time wh en each boat caught somewhat fewer shrimp, and now, each boat is catching a lot less shrimp. Which of the following topics might help your friend understand the source of his problem?

Density - dependent population regulation and intrinsic characteristics of population growth

Exponential growth curves and unlimited environmental resources

Density - independent population regulation and chance occurrence

Pollution effects of a natural environment and learned shrimp behavior

A K - selected population switching to an r - selected population

Carrying capacity is

Seldom reached by marine producers and consumers because of the vast resources of the ocean.

The maximum population size that a particular environment can support.

Fixed for most species over most of their range most of the time.

Determined by density and dispersion data.

The term used to describe the stress a population undergoes due to limited resources.

Which of the following is a density - independent f actor limiting human population growth?

Social pressure for birth control

Earthquakes

Plagues

Famines

Pollution

A population of white - footed mice becomes severely overpopulated in a habitat that has been disturbed by human activity. Som etimes intrinsic factors cause the population to increase in mortality and lower reproduction rates in reaction to the stress of overpopulation. Which of the following is an example of intrinsic population control?

Owl populations frequent the area more often because of increased hunting success.

Females undergo hormonal changes that delay sexual maturation and many individuals suffer depressed immune systems and die due to the stress of overpopulation.

Clumped dispersion of the population leads to increased spread of disease and parasites resulting in a population crash.

All of the resources (food and shelter) are used up by overpopulation and much of the population dies of exposure and/or starvation.

Because the individuals are vulnerable th ey are more likely to die off if a drought or flood were to occur.

Consider several human populations of equal size and net reproductive rate, but different in age structure. The population that is likely to grow the most during the next 30 years is the one with the greatest fraction of people in which age range?

50 to 60 years

40 to 50 years

30 to 40 years

20 to 30 years

10 to 20 years

The observation that members of a population are uniformly distributed suggests that

The size of the area occupied by the population is increasing.

Resources are distributed unevenly.

The members of the population are competing for access to a resource.

The members of the population are neither attracted to nor repelled by one another.

The density of the population is low.

Population ecologists follow the fate of same - age cohorts to

Determine a populationʹs carrying capacity.

Determine if a population is regulated by density - dependent processes.

Determine the birth rate and death rate of each group in a population.

Determine the factors that regulate the size of a population.

Determine if a populationʹs growth is cyclic.

According to the logistic growth equation dN / dt = r max N ( K — N )/ K ,

The number of individuals a dded per unit time is greatest when N is close to zero.

The per capita growth rate ( r ) increases as N approaches K .

Population growth is zero when N equals K .

The population grows exponentially when K is small.

The birth rate ( b ) approaches zero as N approaches K .

A populationʹs carrying capacity

Can be accurately calculated using the logistic growth model.

Generally remains constant over time.

Increases as the per capita growth rate ( r) decreases.

May change as e nvironmental conditions change.

Can never be exceeded.

Which pair of terms most accurately describes life history traits for a stable population of wolves?

Semelparous; r - selected

Semelparous; K - selected

Iteroparous; r - selected

Iteroparo us; K - selected

Iteroparous; N - selected

During exponential growth, a population always

Grows by thousands of individuals.

Grows at its maximum per capita rate.

Quickly reaches its carrying capacity.

Cycles through time.

Loses some indi viduals to emigration.

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