Chapter 52

The number of individuals per unit area or volume of habitat is called the population’s: a. geographical range. b. dispersion pattern. c. density. d. size. e. age structure.

A uniform dispersion pattern implies that members of a population: a. cooperate in rearing their offspring. b. work together to escape from predators. c. use resources that are patchily distributed. d. may experience intraspecific competition for vital resources. e. have no ecological interactions with each other.

The model of exponential population growth predicts that the per capita population growth rate \(r.\) a. does not change as a population gets larger. b. gets larger as a population gets larger. c. gets smaller as a population gets larger. d. is always at its maximum level \(\left(r_{\max }\right)\). e. fluctuates on a regular cycle.

According to the logistic model of population growth, the absolute number of individuals by which a population grows during a given time period: a. gets steadily larger as the population size increases. b. gets steadily smaller as the population size increases. c. remains constant as the population size increases. d. is highest when the population is at an intermediate size. e. fluctuates on a regular cycle.

One reason why human populations have been able to sidestep the factors that usually control population growth is that: a. the carrying capacity for humans has remained constant since humans first evolved. b. agriculture and industrialization have increased the carrying capacity for our species. c. the population growth rate (r) for the human population has always been small. d. the age structure of human populations has no impact on its population growth. e. plagues have killed off large numbers of humans at certain times in the past.

One day you caught and marked 90 butterflies in a population. A week later, you returned to the population and caught 80 butterflies, including 16 that had been marked previously. What is the size of the butterfly population? a. 170 b. 450 c. 154 d. 186 e. 106

A population of 1,000 individuals experiences 462 births and 380 deaths in 1 year. What is the value of \(r\) for this population? a. \(0.842 /\) individual/year b. \(0.462 /\) individual/year c. 0.380/individual/year d. \(0.820 /\) individual/year e. \(0.082 /\) individual/year

Which example might reflect density-dependent regulation of population size? a. An exterminator uses a pesticide to eliminate carpenter ants from a home. b. Mosquitoes disappear from an area after the first frost. c. The lawn dies after a month-long drought. d. Storms blow over and kill all the willow trees along a lake. e. The size of a clam population declines as the number of predatory herring gulls explodes.

A \(K\) -selected species is likely to exhibit: a. a Type I survivorship curve and a short generation time. b. a Type II survivorship curve and a short generation time. c. a Type III survivorship curve and a short generation time. d. a Type I survivorship curve and a long generation time. e. a Type II survivorship curve and a long generation time.

How could you define the worldwide carrying capacity for humans? What factors would you have to take into account?

Choose an animal or plant species that lives in your environment and identify the density-dependent and density-independent factors that might influence its population size. How could you demonstrate conclusively that the factors are either density-dependent or density-independent?

Many city-dwellers have noted that the density of cockroaches in apartment kitchens appears to vary with the habits of the occupants: people who wrap food carefully and clean their kitchen frequently tend to have fewer arthropod roommates than those who leave food on kitchen counters and clean less often. Interpret these observations from the viewpoint of a population ecologist.

Design an experiment using fruit flies or some other small laboratory animal to test the hypothesis that delaying the age of first reproduction will decrease a population's per capita birth rate. Your experimental design should include experimental and control groups as well as details about your experimental methods and the data you would collect.

Thinking Many animals, including humans and other primates, live long beyond their reproductive years. Develop an evolutionary hypothesis to explain this observation, and design a study that might test it.