Biological Science

Scott Freeman, Lizabeth Allison, Michael Black

Chapter 54

Population Ecology - all with Video Answers

Educators

Chapter Questions

Problem 1

What is the defining feature of exponential growth?
a. The population is growing very quickly.
b. The growth rate is constant.
c. The growth rate increases rapidly over time.
d. The growth rate is very high.

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Problem 2

List four factors that define population growth.

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Numerade Educator

Problem 3

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.

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Numerade Educator

Problem 4

True or False? Climate change can influence the population growth of species.

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Numerade Educator

Problem 5

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.

Bryan Lynn

Numerade Educator

Problem 6

Why have population biologists become particularly interested in the dynamics of metapopulations?
a. because humans exist as a metapopulation
b. because whooping cranes exist as a metapopulation
c. because many populations are becoming restricted to small islands of habitat
d. because metapopulations explain why populations occupying large, contiguous areas are vulnerable to extinction.

Bryan Lynn

Numerade Educator

Problem 7

Describe the life-history traits of elephants.
a. high survivorship, high fecundity
b. low survivorship, high fecundity
c. high survivorship, low fecundity
d. low survivorship, low fecundity.

Bryan Lynn

Numerade Educator

Problem 8

Make a table to show what types of traits you would expect to see on the left, middle, and right of the life history continuum (see Figure 54.3 ). Consider growth habit (herbaceous, shrub, or tree) as well as relative disease- and predator-fighting ability, seed size, seed number, and body size.

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Problem 9

Offer a hypothesis to explain why humans have undergone nearexponential growth for over 500 years. Why can't exponential growth continue indefinitely? Describe two examples of densitydependent factors that may influence human population growth.

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Numerade Educator

Problem 10

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.

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Problem 11

Predict which geographic subpopulations of Lacerta vivipara may be most vulnerable to the effects of climate change.

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Problem 12

What is the difference between $r$ (the per capita rate of increase) and $r_{\max }$ (the maximum or intrinsic growth rate)?

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Problem 13

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?

Bryan Lynn

Numerade Educator

Problem 14

Design a system of nature preserves for an endangered species of beetle whose larvae feed on only one species of sunflower. The sunflowers tend to be found in small patches that are scattered throughout dry grassland habitats.

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Problem 15

Make a rough sketch of the age distribution in developing versus developed countries, and explain why the shapes of the diagrams are different. How is AIDS, which is a sexually transmitted disease, affecting the age distribution in countries hard hit by the epidemic?

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Numerade Educator

Problem 16

In most species the sex ratio is at or near 1.00 , meaning that the number of males and females is approximately equal. In China, however, there is a strong preference for male children. According to the 2000 census there, the sex ratio of newborns is almost 1.17 meaning that close to 117 boys are born for every 100 girls. Based on these data, researchers project that China will soon have about 50 million more men than women of marriageable age. Evaluate whether this skewed sex ratio will affect the population growth rate in China.
a. No, growth rate is not affected by males.
b. Yes, growth rate will increase.
c. Yes, growth rate will decrease.
d. No, the sex ratio affects only fecundity.

Bryan Lynn

Numerade Educator