50. Population Ecology

Population ecologists follow the fate of same-age cohorts to a. determine a population's carrying capacity. b. determine the birth rate and death rate of each group in a population. c. determine if a population is regulated by density-dependent processes. d. determine the factors that affect the size of a population.

What is usually true of exponential growth? Select True or False for each statement. T/F The population is growing. T/F The per capita growth rate is constant. T/F The per capita growth rate increases rapidly over time. T/F The per capita growth rate is very high.

A population's carrying capacity a. may change as environmental conditions change. b. can be accurately calculated using the logistic growth model. c. increases as the per capita population growth rate decreases. d. can never be exceeded.

In what populations does exponential growth tend to occur? a. populations that colonize new habitats b. populations that experience intense competition c. populations that experience high rates of predation d. populations that have surpassed their carrying capacity

Explain why a decrease in population growth rate is expected as a nonhuman population approaches carrying capacity.

Scientific study of the population cycles of the snowshoe hare and its predator, the lynx has revealed that a. predation is the dominant factor affecting prey population cycling. b. hares and lynx are so mutually dependent that each species cannot survive without the other. c. both hare and lynx population sizes are affected mainly by abiotic factors. d. the hare population is r-selected and the lynx population is K-selected.

If most individuals in a population are young, why is the population likely to grow rapidly in the future? a. Death rates will be low. b. The population has a skewed age distribution. c. Immigration and emigration can be ignored. d. Many individuals will begin to reproduce soon.

Analyzing ecological footprints reveals that a. Earth's carrying capacity would increase if per capita meat consumption increased. b. current demand by industrialized countries for resources is much smaller than the ecological footprint of those countries. c. it is not possible for technological improvements to increase Earth's carrying capacity for humans. d. the ecological footprint of the United States is large because per capita resource use is high.

Why is there a trade-off between survivorship and fecundity?

Based on current growth rates, Earth's human population in 2019 will be closest to a. 2.5 million. b. 4.5 billion. c. 7.5 billion. d. 10.5 billion.

Which of the following species is most likely to have a Type III survivorship curve? a. humans, Homo sapiens b. common lizards, Zootoca vivipara c. thale cress plants, Arabidopsis thaliana d. lynx cats, Lynx canadensis

The observation that members of a population are uniformly distributed suggests that a. resources are distributed unevenly. b. the members of the population are competing for access to a resource. c.the members of the population are neither attracted to nor repelled by one another. d. the density of the population is low.

Pose a hypothesis to explain why the human population has undergone especially rapid growth over the past 200 years. Describe two examples of density-dependent factors that limit human population growth. Is it possible that humans have surpassed Earth's carrying capacity?

According to the logistic growth equation dNdt=rN(K−N)K a. the number of individuals added per unit time is greatest when N is close to zero. b. the per capita population growth rate increases as N approaches K. c. population growth is zero when N equals K. d. the population grows exponentially when K is small.

Explain why biologists want to maintain (a) 'habitat corridors' that connect populations in a metapopulation, and (b) unoccupied habitat that is appropriate for the species in question.

During exponential growth, a population always a. has a constant per capita population growth rate. b. quickly reaches its carrying capacity. c. cycles through time. d. loses some individuals to emigration.

Indicate what is correct and incorrect about this statement: If lizards want to survive during climate change, they can evolve new life-history traits.

The current carrying capacity of Earth for the human population may have been inflated by                  . a. demographic momentum; b. the tendency for women to want to control family size; c. an artificially low number of density-independent factors; d. our use of fossil fuels; e. recent population crashes

When wild plant and animal populations are logged, fished, or hunted, only the oldest or largest individuals tend to be taken. Many of the commercially important species are long lived and are slow to begin reproducing. If harvesting is not regulated carefully and exploitation is intense, what impact does harvesting have on a population's age structure? How might harvesting affect the population's life table and growth rate?

What is survivorship? What does a survivorship curve show? Explain what the three survivorship curves tell us about humans, squirrels, and clams.

Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem? Researchers hypothesize that the severe winter of 2010 caused the decline in the number of pythons encountered that year. Is cold weather typically a density-dependent factor or a density-independent factor? Explain the difference.

Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem? The data in the graph show the number of pythons that were encountered, not the total number of pythons in the population. Design a mark–recapture experiment to estimate the total population size of pythons, and list at least two assumptions you would be making in your experiment.

Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem? A life table would help researchers make predictions about python population growth. If you were to track a cohort of pythons over time to construct a detailed life table, what kind of data would you want to collect?

Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem? The range of Burmese pythons in Florida is expanding rapidly. List at least one abiotic factor and one biotic factor that might limit the range of pythons.

Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem? Burmese pythons were first found in the wetlands of Everglades National Park in the 1980s, but only rarely. The accompanying graph shows what happened next. Most of the data are derived from chance encounters of pythons on roads and intermittent search effort near roads (pythons are notoriously difficult to find). Despite the variability in search effort, what type of population growth best describes the trend in the data from 2000 to 2020? a. logistic b. exponential c. linear d. logarithmic

Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem? Pythons are generalist predators, consuming more than 75 species of prey including frogs, mice, rabbits, squirrels, porcupines, raccoons, leopards, deer, monkeys, alligators, and birds ranging from wrens to herons. Some surveys showed the disappearance of some animals, such as rabbits and opossums, from areas with pythons. Do you think food availability limits, or could limit, the carrying capacity of Burmese pythons in the Everglades?

Predict the possible consequences of global warming to the net reproductive rate of sea turtles given that the sex ratio of many sea turtles and other reptiles is determined by the temperature of the eggs in the nest; typically, warmer eggs become female and cooler eggs become male.

Which of the following statements about human populations in industrialized countries is correct?

a. Birth rates and death rates are high.

b. Average family size is relatively large.

c. The population has undergone the demographic transition.

d. The survivorship curve is Type II.

According to the diagram, which of the following countries has the greatest human population density?

Which of the following is an example of population density?

To calculate the population density of people in Florida, you would need to know:

Which of the following factors directly impacts the population of rabbits in a meadow?

Suppose a population of rabbits in a forest has an initial population of 500. Over the course of one year, 200 new rabbits are born, and 150 rabbits die. Additionally, 20 rabbits emigrate out of the forest and 50 rabbits immigrate into the forest. What is the population size at the end of the year?

Which of the following would NOT be considered a metapopulation?

Which of the following statements is true?

Which of the following species displays a uniform species dispersion pattern?