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 A) I only B) III only C) I and II only D) II and III only E) 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? A) density B) dispersion C) carrying capacity D) quadrats E) 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 A) 200. B) 500. C) 1,000. D) 10,000. E) 900,000.

During the spring, you are studying the mice that live in a field near your home. There are lots of mice in this field, but you realize that you rarely observe any reproductive females. This most likely indicates A) that there is selective predation on female mice. B) that female mice die before reproducing. C) that this habitat is a good place for mice to reproduce. D) that you are observing immigrant mice. E) that the breeding season is over

You are observing a population of lizards when you notice that the number of adults has increased and is higher than previously observed. One explanation for such an observation would include A) reduction in death rate. B) increased immigration. C) increased emigration. D) decreased emigration. E) increased birth rate.

The most common kind of dispersion in nature is A) clumped. B) random. C) uniform. D) indeterminate. E) dispersive.

Uniform spacing patterns in plants such as the creosote bush are most often associated with A) chance. B) patterns of high humidity. C) the random distribution of seeds. D) competitive interactions among individuals in the population. E) the concentration of nutrients within the populationʹs range.

Which of the following groups would be most likely to exhibit uniform dispersion? A) red squirrels, who actively defend territories B) cattails, which grow primarily at edges of lakes and streams C) dwarf mistletoes, which parasitize particular species of forest tree D) moths in a city at night E) lake trout, which seek out deep water

A table listing such items as age, observed number of organisms alive each year, and life expectancy is known as a (an) A) life table. B) mortality table. C) survivorship table. D) rate table. E) insurance table.

Life tables are most useful in determining which of the following? A) carrying capacity B) the fate of a cohort of newborn organisms throughout their lives C) immigration and emigration rates D) population dispersion patterns E) reproductive rates

In order to construct a reproductive table for a sexual species, you need to A) assess sperm viability. B) keep track of all of the offspring of a cohort. C) keep track of the females in a cohort. D) keep track of all of the offspring of the females in a cohort. E) 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? A) counting the number of prairie dog burrows per hectare B) counting the number of times a 1 kilometer transect is intersected by tracks of red squirrels after a snowfall C) counting the number of coyote droppings per hectare D) multiplying the number of moss plants counted in 10, 1m2 quadrats by 100 to determine the density per kilometer2. E) 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 clips. Using the capture-recapture estimate, the lake trout population size could be closest to which of the following? A) 200 B) 250 C) 400 D) 800 E) 40,000

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 emigration, and no individuals have been added by birth or eliminated by death during the course of the estimate. A) I only B) II only C) I and II only D) II and III only E) I, II, and III

Long-term studies of Beldingʹs ground squirrels show that immigrants move nearly 2 km from where they are born and make up 1 to 8% of the males and 0.7 to 6% of the females in other populations. On an evolutionary scale, why is this significant? A) These immigrants make up for the deaths of individuals keeping the other populationsʹ size stable. B) Young reproductive males tend to stay in their home population and are not driven out by other territorial males. C) These immigrants provide a source of genetic diversity for the other populations. D) Those individuals that emigrate to these new populations are looking for less crowded conditions with more resources. E) Gradually, the populations of ground squirrels will move from a uniform to a clumped population pattern of dispersion.

Demography is the study of A) the vital statistics of populations and how they change over time. B) death and emigration rates of a population at any moment in time. C) the survival patterns of a population. D) life expectancy of individuals within a population. E) reproductive rates of a population during a given year.

Natural selection has led to the evolution of diverse natural history strategies, which have in common A) many offspring per reproductive episode. B) limitation only by density-independent limiting factors. C) adaptation to stable environments. D) maximum lifetime reproductive success. E) relatively large offspring.

Natural selection involves energetic trade-offs between A) choosing how many offspring to produce over the course of a lifetime and how long to live. B) producing large numbers of gametes when employing internal fertilization versus fewer numbers of gametes when employing external fertilization. C) the emigration of individuals when they are no longer reproductively capable or committing suicide. D) increasing the number of individuals produced during each reproductive episode with a corresponding decrease in parental care. E) 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 A) life expectancy, birth rate, and death rate. B) number of reproductive females in the population, age structure of the population, and life expectancy. C) age when reproduction begins, how often reproduction occurs, and how many offspring are produced per reproductive episode. D) how often reproduction occurs, life expectancy of females in the population, and number of offspring per reproductive episode. E) the number of reproductive females in the population, how often reproduction occurs, and death rate.

Which of the following pairs of reproductive strategies is consistent with energetic trade-off and reproductive success? A) Pioneer species of plants produce many very small, highly airborne seeds, while large elephants that are very good parents produce many offspring. B) Female rabbits that suffer high predation rates may produce several litters per breeding season, and coconuts produce few fruits, but most survive when they encounter proper growing conditions. C) Species that have to broadcast to distant habitats tend to produce seeds with heavy protective seed coats, and animals that are caring parents produce fewer offspring with lower infant mortality. D) Free-living insects lay thousands of eggs and provide no parental care, while flowers take good care of their seeds until they are ready to germinate. E) Some mammals will not reproduce when environmental resources are low so they can survive until conditions get better, and plants that produce many small seeds are likely found in stable environments.

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. A) 120 individuals added B) 40 individuals added C) 20 individuals added D) 400 individuals added E) 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, A) the large population will add more individuals per unit time. B) the small population will add more individuals per unit time. C) the two populations will add equal numbers of individuals per unit time. D) the J-shaped growth curves will look identical. E) 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) a diagonal line, getting higher with each generation. B) an ʺS,ʺ increasing with each generation. C) an upside-down ʺU.ʺ D) a ʺJ,ʺ increasing with each generation. E) an ʺSʺ that ends with a vertical line.

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? A) birth rate and death rates B) dispersion C) density D) carrying capacity E) 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 people, approximately how many births occurred in the United States in 2005? A) 3,800 B) 38,000 C) 380,000 D) 3,800,000 E) 38,000,000

Exponential growth of a population is represented by dN/dt = A) rN K B) rN C) rN(K+N) D) rN (K-N) K E) rN (N-K) K

Logistic growth of a population is represented by dN/dt = A) rN K B) rN C) rN(K+N) D) rN (K-N) K E) rN (N-K) K

As N approaches K for a certain population, which of the following is predicted by the logistic equation? A) The growth rate will not change. B) The growth rate will approach zero. C) The population will show an Allee effect. D) The population will increase exponentially. E) 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 population? A) r B) N C) rN D) K E) dt

Which of the following might be expected in the logistic model of population growth? A) As N approaches K, b increases. B) As N approaches K, r increases. C) As N approaches K, d increases. D) Both A and B are true. E) Both B and C are true.

In models of sigmoidal (logistic) population growth, A) population growth rate slows dramatically as N approaches K. B) new individuals are added to the population most rapidly at the beginning of the populationʹs growth. C) only density-dependent factors affect the rate of population growth. D) only density-independent factors affect the rate of population growth. E) carrying capacity is never reached.

The Allee effect is used to describe a population that A) has become so small that it will have difficulty surviving and reproducing. B) has become so large it will have difficulty surviving and reproducing. C) approaches carrying capacity. D) exceeds carrying capacity. E) is in crash decline.

Which of the following is the pattern of spacing for individuals within the boundaries of the population? A) cohort B) dispersion C) Allee effect D) iteroparous E) semelparous

Pacific salmon or annual plants illustrate which of the following? A) cohort B) dispersion C) Allee effect D) iteroparous E) semelparous

Which of the following describes having more than one reproductive episode during a lifetime? A) cohort B) dispersion C) Allee effect D) iteroparous E) semelparous

Density-dependent factors are related to which of the following? A) cohort B) dispersion C) Allee effect D) iteroparous E) semelparous

Which of the following is true? A) K-selection operates in populations where populations fluctuate well below the carrying capacity. B) r-selection occurs in populations whose densities are very near the carrying capacity. C) Different populations of the same species will be consistently r- or K-selected. D) r- and K-selection are two extremes of a range of life history strategies. E) r-selection tends to maximize population size, not the rate of increase in population size.

The life history traits favored by selection are most likely to vary with A) fluctuations in K. B) the shape of the J curve. C) the maximum size of a population. D) population density. E) population dispersion

In which of the following habitats would you expect to find the largest number of K-selected individuals? A) a recently abandoned agricultural field in Ohio B) the sand dune communities of south Lake Michigan C) the flora and fauna of a coral reef in the Caribbean D) South Florida after a hurricane E) a newly emergent volcanic island

Which of the following characterizes relatively K-selected populations? A) offspring with good chances of survival B) many offspring per reproductive episode C) small offspring D) a high intrinsic rate of increase E) early parental reproduction

Which of the following statements about the evolution of life histories is correct? A) Stable environments with limited resources favor r-selected populations. B) K-selected populations are most often found in environments where density-independent factors are important regulators of population size. C) Most populations have both r- and K-selected characteristics that vary under different environmental conditions. D) The reproductive efforts of r-selected populations are directed at producing just a few offspring with good competitive abilities. E) K-selected populations rarely approach carrying capacity.

Your friend comes to you with a problem. It seems his shrimp boats arenʹt catching 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 when 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? A) density-dependent population regulation and intrinsic characteristics of population growth B) exponential growth curves and unlimited environmental resources C) density-independent population regulation and chance occurrence D) pollution effects of a natural environment and learned shrimp behavior E) a K-selected population switching to an r-selected population

Carrying capacity is A) seldom reached by marine producers and consumers because of the vast resources of the ocean. B) the maximum population size that a particular environment can support. C) fixed for most species over most of their range most of the time. D) determined by density and dispersion data. E) the term used to describe the stress a population undergoes due to limited resources.

Which of the following can contribute to density-dependent regulation of populations? A) the removal of toxic waste by decomposers B) intraspecific competition for nutrients C) earthquakes D) floods E) weather catastrophes

Field observation suggests that populations of a particular species of herbivorous mammal undergo cyclic fluctuations in density at three- to five-year intervals. Which of the following represent (a) plausible explanation(s) of these cycles? A) Periodic crowding affects the endocrine system, resulting in increased aggressiveness. B) Increases in population density lead to increased rates of predation. C) Increases in rates of herbivory lead to changes in the nutritive value of plants used as food. D) Increases in population density lead to more proximal infestations of parasites to host animals. E) All of the above are plausible explanations of population cycling.

Which of the following is an incorrect statement about the regulation of populations? A) The logistic equation reflects the effect of density-dependent factors, which can ultimately stabilize populations around the carrying capacity. B) Density-independent factors have an increasingly greater effect as a populationʹs density increases. C) High densities in a population may cause physiological changes that inhibit reproduction. D) Because of the overlapping nature of population-regulating factors, it is often difficult to precisely determine their cause-and-effect relationships. E) The occurrence of population cycles in some populations may be the result of crowding or lag times in the response to density-dependent factors.

Which of the following is a density-independent factor limiting human population growth? A) social pressure for birth control B) earthquakes C) plagues D) famines E) pollution

A population of white-footed mice becomes severely overpopulated in a habitat that has been disturbed by human activity. Sometimes 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? A) Owl populations frequent the area more often because of increased hunting success. B) Females undergo hormonal changes that delay sexual maturation and many individuals suffer depressed immune systems and die due to the stress of overpopulation. C) Clumped dispersion of the population leads to increased spread of disease and parasites resulting in a population crash. D) All of the resources (food and shelter) are used up by overpopulation and much of the population dies of exposure and/or starvation. E) Because the individuals are vulnerable they are more likely to die off if a drought or flood were to occur.

Why is territoriality an adaptive behavior for songbirds maintaining populations at or near their carrying capacity? A) Songbirds expend a tremendous amount of energy defending territories so that they spend less time feeding their young and fledgling mortality increases. B) Only the fittest males defend territories and they attract the fittest females so the best genes are conveyed to the next generation. C) Songbird males defend territories commensurate with the size from which they can derive adequate resources for themselves, their mate, and their chicks. D) Many individuals are killed in the ritualistic conflicts that go along with territorial defense. E) Songbirds make improvements to the territories they inhabit so that they can all enjoy larger clutches and successfully fledged chicks.

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? A) 50 to 60 years B) 40 to 50 years C) 30 to 40 years D) 20 to 30 years E) 10 to 20 years

Most ecologists believe that the average global carrying capacity for the human population is between A) 5 and 6 billion. B) 6 and 8 billion. C) 10 and 15 billion. D) 15 and 20 billion. E) 20 and 25 billion.

An ecological footprint is a construct that is useful A) for a person living in a developed nation to consider to make better choices when using global food and energy resources. B) for a person living in a developing country to see how much of the worldʹs resources are left for him/her. C) in converting human foodsʹ meat biomass to plant biomass. D) in making predictions about the global carrying capacity of humans. E) in determining which nations produce the least amount of carbon dioxide from the burning of fossil fuels.