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Environment: The Science Behind the Stories, 3e (Withgott)
Chapter 5 Evolution, Biodiversity, and Population Ecology
5.1 Graph and Figure Interpretation Questions
Use Figure 5.1 to answer the following questions.
A flock of 100 small, bright yellow and brown finches is blown off course and ends up on a large island
where there is a lot of open, grassy ground, and low hills. There are mammals, many plants, some insects,
lizards, and a few hawks, but there are no other small birds. There are two types of plants with edible
seeds, a very small-seeded grass, and a large-seeded bush.
1) Over many years, the population of finches on the island ________.
A) begins to look like graph (a), directional selection, with regard to beak size
B) begins to look like graph (b), stabilizing selection, with regard to beak size
C) begins to look like graph (c), disruptive selection, with regard to beak size
D) goes extinct because there is nothing that they can manage to eat
E) doesn't change; they maintain their original diversity
Answer: C
Diff: 3
Objective: 5.1 The process of natural selection
1
2) The hawks on the island have always eaten insects, lizards, and mammals, but they find the
brightest yellow finches to be easy prey as well. Over many years, the population of finches
on the island ________.
A) begins to look like graph (a), directional selection, with regard to coloration
B) begins to look like graph (b), stabilizing selection, with regard to coloration
C) begins to look like graph (c), disruptive selection, with regard to coloration
D) goes extinct because the hawks eat them all
E) doesn't change; they maintain their original diversity
Answer: A
Diff: 3
Objective: 5.1 The process of natural selection
3) Over many years, the population of finches on the island ________.
A) begins to look like graph (a), directional selection, with regard to wing length
B) begins to look like graph (b), stabilizing selection, with regard to wing length
C) begins to look like graph (c), disruptive selection, with regard to wing length
D) goes extinct because the wings do not change
E) doesn't change; they maintain their original diversity
Answer: A
Diff: 3
Objective: 5.1 The process of natural selection
2
5.2 Matching Questions
Match the following.
1) Multiple interacting species
that live in the same area
Diff: 1
Objective: 5.4 Levels of ecological
organization
2) Communities and the abiotic
material with which their
members interact
Diff: 1
Objective: 5.4 Levels of ecological
organization
3) Specific environment in
which an organism lives
A) r-selected
B) ecosystems
C) environmental cooperation
D) population
E) ecotones
F) population potential
G) population density
H) endemic
Diff: 1
Objective: 5.4 Levels of ecological
organization
4) Number of individuals
within a population per unit
area
Diff: 1
Objective: 5.6 Concepts of population
ecology
I) niche
J) habitat
K) community
L) environmental resistance
5) Stabilizes a population at its
carrying capacity
Diff: 1
Objective: 5.5 Characteristics that
predict population growth
6) species occurring in only one
area
Diff: 1
Objective: 5.6 Concepts of population
ecology
1) K
2) B
3) J
4) G
3
5) L
6) H
5.3 Short Answer Questions
1) What are the two parts to the lesson learned from the Monteverde rain forest?
Answer: Extinction is common as a consequence of human disturbance to natural ecosystems.
Equally important is that species are disappearing at rates higher than we are
discovering them.
Diff: 2
Objective: 5.7 Conservation of biodiversity
2) What is biological diversity, and what specific categories of diversity are included in the
definition?
Answer: It is the sum total of all organisms in an area, taking into account the diversity of
species, their genes, their populations, and their communities.
Diff: 1
Objective: 5.3 Evolution results in biodiversity
3) What is habitat selection, and how does it differ for different organisms?
Answer: Habitat selection happens when an organism selects a habitat to live in from among
the range of options it encounters. Criteria differ among organisms. For soil
organisms, for example, chemistry may be important, whereas for a squirrel, tree
density might be important.
Diff: 2
Objective: 5.6 Concepts of population ecology
4) Write the equation used to determine growth rate.
Answer: Growth rate = (crude birth rate + immigration rate) – (crude death rate + emigration
rate)
Diff: 1
Objective: 5.5 Characteristics that predict population growth
5) Differentiate between habitat and niche.
Answer: The habitat is the physical location where an organism lives, all of the abiotic and
biotic factors that describe the location. The niche is the full ecological role that a
species is capable of playing, not only where it lives but what it eats, what eats it, what
it competes with for resources.
Diff: 1
Objective: 5.4 Levels of ecological organization
6) Differentiate between generalist and specialist species.
Answer: A generalized species will have breadth, for example, in its selection of food or usable
habitats, but a specialist will be adapted to one particular food choice or habitat.
Specialized species are often at greater risk when habitats are impacted by human or
natural disturbances.
Diff: 2
Objective: 5.4 Levels of ecological organization
7) The departure of individuals from a population is called ________.
Answer: emigration
Diff: 1
Objective: 5.5 Characteristics that predict population growth
4
8) The innate reproductive capacity of a species is its ________.
Answer: biotic potential
Diff: 1
Objective: 5.5 Characteristics that predict population growth
5.4 Multiple-Choice Questions
1) Extinction is ________.
A) a natural process
B) not caused by human disturbance
C) the loss of communities from the planet
D) proceeding more slowly now than at any other time
E) something that occurs only rarely
Answer: A
Diff: 1
Objective: 5.3 Evolution results in biodiversity
2) Most extinction is ________.
A) the result of catastrophe
B) gradual
C) the result of slow climate change
D) problematic for generalists
E) not often a problem for endemics
Answer: B
Diff: 2
Objective: 5.3 Evolution results in biodiversity
3) The two processes that determine the world's current biodiversity are ________.
A) allopatric and sympatric speciation
B) mutation and cleavage
C) endemism and climate change
D) extinction and speciation
E) breeding and ecotourism
Answer: D
Diff: 2
Objective: 5.3 Evolution results in biodiversity
4) A population is a ________.
A) group of individuals of interacting species that live in one area
B) group of individuals of interacting species that interact in multiple ecosystems
C) group of individuals of a single species that live in one area
D) subset of bacteria that grow on a petri dish
E) group of cells that have similar function
Answer: C
Diff: 1
Objective: 5.4 Levels of ecological organization
5
5) Endemic species ________.
A) are generalist organisms
B) cause disease
C) are invasive species that cause extinction
D) have high rates of mutations that lead to large numbers of offspring species
E) are found only in one place on the planet
Answer: E
Diff: 1
Objective: 5.6 Concepts of population ecology
6) The functional role of a species in its community is its ________.
A) habitat
B) place in the food chain
C) selection
D) niche
E) evolution
Answer: D
Diff: 1
Objective: 5.4 Levels of ecological organization
7) High population density can ________.
A) hinder organisms from finding mates
B) decrease biodiversity within a species
C) decrease competition
D) decrease the use of resources
E) increase the incidence of disease transmission
Answer: E
Diff: 2
Objective: 5.6 Concepts of population ecology
8) Population distribution describes ________.
A) placement of a species around the globe
B) placement of a species within a country's boundaries
C) spatial arrangement of individuals of a single species within a particular area or
ecosystem
D) spatial arrangement of multiple species within a particular area
E) how near or far away individuals in a population are from a resource, such as water
Answer: C
Diff: 2
Objective: 5.6 Concepts of population ecology
9) Age pyramids, used to show the age structure of a population, generally ________.
A) have no inherent value for predicting growth
B) cannot predict possible species declines in numbers
C) have bars that represent sizes of individual organisms
D) indicate the relative numbers (frequency, or percentage) of individuals in each age
class
E) indicate the total numbers of individuals in each age class
Answer: D
Diff: 2
Objective: 5.5 Characteristics that predict population growth
6
10) Unregulated populations tend to increase by ________.
A) linear growth
B) exponential growth
C) pyramidal growth
D) emigration
E) immigration
Answer: B
Diff: 1
Objective: 5.5 Characteristics that predict population growth
11) The carrying capacity is the ________.
A) maximum population size that a given environment can sustain
B) greatest number of different niches possible in a given area
C) potential growth in the number of species in a given area
D) limitation on numbers of species in a community
E) average number of offspring carried to term by a species
Answer: A
Diff: 1
Objective: 5.6 Concepts of population ecology
12) Density-dependent factors ________.
A) include the effects of a hard freeze on an entire community
B) include the effects of a hard freeze on a single species within a community
C) cause decreases in the number of species in an ecosystem
D) include the effects of rainfall on an entire community
E) include the effects of disease and predators on a single species within a community
Answer: E
Diff: 2
Objective: 5.6 Concepts of population ecology
13) Groups of organisms with low biotic potential, such as gray whales, that produce at most
one offspring every other year, are said to be ________.
A) r-selected
B) K-selected
C) density-independent organisms
D) cannot be determined from information given
E) high in biotic potential because of their size, like the grey whale
Answer: B
Diff: 2
Objective: 5.6 Concepts of population ecology
14) Heavy rains and mudslides cause a river to change course, isolating two groups of lizards
from one another. Over a long period of time, ________.
A) one group will probably become an endemic species
B) both groups will probably become native species
C) the groups will probably become genetically different, and speciation may occur
D) one or both groups will probably emigrate
E) one or both groups will probably become invasive species
Answer: C
Diff: 2
Objective: 5.3 Evolution results in biodiversity
7
15) Which of the following would be most vulnerable to extinction?
A) a moth, brought to the United States for silk production, escaping into the wild and
becoming established
B) an orchid endemic to an area where logging is occurring
C) a healthy plant, such as a pine tree, that completely dominates its native environment
D) a migratory flock of warblers stopping along its winter route to feed on local resources
that are now gone and replaced by a suburb
E) a mold that attacks wheat in the field
Answer: B
Diff: 2
Objective: 5.7 Conservation of biodiversity
16) The destruction of ecosystems is not a problem ________.
A) because restoration ecology can restore ecosystems
B) because humans can find and make their own resources
C) because zoos and gardens contain most important species and breeding technologies
are improving
D) because our understanding of genetics allows us to restore populations
E) incorrect; the destruction of ecosystems is always a problem
Answer: E
Diff: 2
Objective: 5.7 Conservation of biodiversity
17) A small moth pollinates native trees when they bloom in April. Some of the moths emerge in
early March and discover a different blooming shrub to use as a resource. This is an example
of what, over time, could be ________.
A) sympatric speciation
B) allopatric speciation
C) an invasive species
D) an extinction for the original population
E) a change in age structure of the original population
Answer: A
Diff: 3
Objective: 5.1 The process of natural selection
18) One example of artificial selection is ________.
A) crossing a lion and a tiger to get a sterile animal called a liger
B) gypsy moths as an invasive species
C) pet dogs that have gone wild, are mating with coyotes, and live in packs
D) humans placing a gene for human insulin into a flower
E) broccoli and brussels sprouts
Answer: E
Diff: 3
Objective: 5.2 Supporting lines of evidence for natural selection
8
19) In a population of field mice, an example of an adaptive trait that could help with
reproduction and/or survival would be ________.
A) being brightly colored so other mice could see you
B) needing to eat more food than other mice your size
C) spending more time running around on the ground looking for better seeds
D) having a bit more fur to withstand cold weather
E) having shorter legs to be lower to the ground
Answer: D
Diff: 3
Objective: 5.1 The process of natural selection
20) A number of coyotes move into an area and begin to eat a population of small harvest mice.
After several years, the harvest mice are much speedier runners than before the coyotes
came. This is an example of ________.
A) stabilizing selection
B) directional selection
C) disruptive selection
D) allopatric speciation
E) sympatric speciation
Answer: B
Diff: 2
Objective: 5.1 The process of natural selection
21) Which of the following would represent a clumped population dispersion pattern?
A) a forest of pine trees
B) oaks planted on city streets
C) a pod of 40 migrating gray whales
D) eagles nesting in the Grand Canyon
E) earthworms in the soil of a garden
Answer: C
Diff: 2
Objective: 5.6 Concepts of population ecology
22) A Type I survivorship curve, with higher death rates at older ages, is typical of ________.
A) redwood trees
B) large open-water ocean fish, such as tuna
C) dandelions
D) large mammals such as gorillas
E) large reptiles such as alligators
Answer: D
Diff: 2
Objective: 5.5 Characteristics that predict population growth
23) An example of a density-independent factor would be ________.
A) blight (a mold disease) in a wheat field
B) cold weather causing the lake to freeze
C) nest sites for a flock of warblers
D) a plant parasite, such as mistletoe
E) a grass that is wind pollinated
Answer: B
Diff: 2
Objective: 5.6 Concepts of population ecology
9
24) Which of the following pairs contains, first, an r-selected organism and, second, a K-selected
organism?
A) elephant; whale
B) elephant; pine tree
C) pine tree; dandelion
D) dandelion; pine tree
E) grasshopper; whale
Answer: E
Diff: 3
Objective: 5.6 Concepts of population ecology
25) A coyote, which can alter its food intake to match seasonal abundance of plants, fruits, or
small animals, is considered to be ________.
A) a generalist, able to be flexible
B) a specialist, able to specialize on whatever is available at the time
C) an endemic, able to be flexible
D) density independent and resource neutral
E) an organism with a Type II survivorship curve
Answer: A
Diff: 2
Objective: 5.6 Concepts of population ecology
26) A species has evolved an asexual mode of reproduction by having offspring develop from
unfertilized eggs. Which of the following will be true of this species' response to natural
selection?
A) There will be more deaths from natural selection because there is no mutation
B) There will be less genetic variation from recombination and a risk of not adapting
quickly to environmental change
C) the species will increase in numbers because genetic variation is increased
D) the species will compensate for loss of genetic variation by hybridizing with other
species
E) there will be fewer deaths from natural selection because sexual recombination always
leads to extinction
Answer: B
Diff: 3
Objective: 5.1 The process of natural selection
5.5 True/False Questions
1) Paleontologists calculate that the average time a species spends on Earth is between 1 – 10
million years.
Answer: TRUE
Diff: 1
Objective: 5.1 The process of natural selection
2) A population that is limited by a resource is expected to have an exponential growth curve.
Answer: FALSE
Diff: 1
Objective: 5.5 Characteristics that predict population growth
3) Ants are K-strategists.
Answer: FALSE
Diff: 1
Objective: 5.5 Characteristics that predict population growth
10
4) Ecotourism is both beneficial and harmful to an area.
Answer: TRUE
Diff: 1
Objective: 5.7 Conservation of biodiversity
5) One line of evidence for natural selection is the obvious results from the artificial selection
that humans have performed on plants and on animals.
Answer: TRUE
Diff: 1
Objective: 5.2 Supporting lines of evidence for natural selection
5.6 Essay Questions
1) Briefly describe speciation. Differentiate between allopatric and sympatric speciation.
Answer: When mutations occur in one population that are not passed to another population, or
if natural selection favors genes in one population and not the other, speciation can
occur if gene flow becomes restricted permanently between the two populations (i.e.,
they can no longer mate and produce fertile offspring). If a physical boundary such as
a stream divides the two populations, restricting gene flow between them, and a
speciation event occurs, this is termed allopatric speciation. If it occurs in one location
without a physical barrier, this is sympatric speciation.
Diff: 1
Objective: 5.1 The process of natural selection
2) Describe the sixth mass extinction event, when it occurred, and its specific causes.
Answer: Currently, most biologists believe that Earth is in the throes of its sixth mass extinction
event and that we are the cause. The changes to Earth's environment by human
population growth, resource use, and development have greatly altered conditions for
many species, have driven many to extinction already, and are threatening countless
more. The alteration and outright destruction of natural habitats, the hunting and
harvesting of species, pollution and the introduction of invasive species from one
place to another have contributed to the threat to Earth's biodiversity.
Diff: 2
Objective: 5.7 Conservation of biodiversity
3) Differentiate between exponential and logistic growth curves. Give examples of the
conditions under which each would occur.
Answer: Exponential growth (a J-shaped curve) is growth when there are no constraints. This
occurs when a population is small and environmental conditions are ideal for the
organism in question. Mold on a piece of bread and bacteria colonizing a dead animal
are examples. Logistic growth (S-shaped growth curve) rises exponentially at first and
then begins to level off as the effects of limiting factors become stronger. A population
introduced into a new environment where there are other organisms will experience
limitations quickly, and these limitations will limit the population growth.
Diff: 3
Objective: 5.5 Characteristics that predict population growth
11
4) Is a carrying capacity a fixed entity? Discuss the role of humans in regulating carrying
capacity for the human species and in altering the carrying capacity for other species.
Answer: While all organisms are subject to environmental resistance, they may be capable of
altering their environment to reduce environmental resistance, or environmental
conditions may change naturally to set a new carrying capacity. Humans can alter
their own carrying capacity by finding resources and through technology, but other
species have less flexibility in altering their carrying capacity. Humans often alter the
carrying capacity for other species by altering climate. An example is the golden toad,
whose habitat lacked enough moisture. Humans can encroach on an area and reduce
breeding areas, food resources, or alter trophic structure within an ecosystem through
hunting.
Diff: 3
Objective: 5.6 Concepts of population ecology
5) A population of quail live in an area of prairie grasslands. In good years, a pair of quail can
have four clutches of young, with as many as 12 to 14 eggs in each clutch. Despite this, the
population size remains stable over the long term. Discuss the population structure, its
potential for growth, and its possible limiting factors, using at least four of the terms you
learned in this chapter.
Answer: Students might discuss the r-selection strategy of quail and their potential for
exceeding the carrying capacity in a year with good weather and plentiful food, an
exponential growth rate. They might talk about the population dispersion (clumped).
They might choose to look at the age distribution or draw an age-structure diagram,
illustrating the large number of eggs and chicks and the rapid loss of young. Densityindependent factors would include things such as weather and drought or floods.
Some density dependent factors might be disease, predators, available nesting sites,
and the amount of food available.
Diff: 3
Objective: 5.6 Concepts of population ecology
6) A species of bird had an original range covering the entire eastern half of the U.S. from New
England west to the Mississippi and then south to Florida. During a period of glaciation, the
eastern part of the population was cut off from the western part for 2000 years. Then the
glacier melted and the birds' range was reestablished. During the separation, the western
birds evolved a slightly different song and a darker wing color. Ornithologists are now
studying this species to determine whether speciation has taken place. What evidence will
the look for in their study?
Answer: Among many observation that can be made, the researchers will have to look at the
ability of eastern and western birds to recognize one another, court and mate. If
mating does occur, they will have to observe whether or not any eggs are laid in the
nest and whether any offspring hatch. They will have to discover whether the eastwest matings produce more or less offspring than east-east and west-west matings.
Finally, if offspring are produced and can in turn produce a second generation of
hybrids, the researchers may conclude that these birds still function as a single
species. If there are no viable hybrids nor if the matings are blocked at an earlier stage,
they may conclude that speciation has indeed taken place.
Diff: 3
Objective: 5.3 Evolution results in biodiversity
12
5.7 Scenario-Based Questions
Read the following scenario and answer the questions below.
The Kaibab Plateau in southern Utah and northern Arizona is a high, isolated, peninsula-like area about
60 miles from north to south and approximately 15 to 25 miles wide, with elevations up to 10,000 feet. It is
bordered by the Grand Canyon on the south and east, by Kanab Creek and Snake Gulch on the west, and
by high desert on the north. In the early 1900s, ranchers had been grazing many cattle there for
generations, and the land showed some grazing damage. Heavy hunting pressure, in combination with
the cattle grazing, had reduced the population of Kaibab deer to only about 4,000.
In 1906, President Theodore Roosevelt established the Grand Canyon National Game Preserve on the
Kaibab Plateau in an effort to protect the mule deer from overhunting by humans and from predation.
Deer hunting ceased, and open season was declared on cougars, wolves, and coyotes.
1) What made the Kaibab Plateau so ideal for attempting to control and improve the deer
population?
A) It was open land where animals could freely move to and from other areas.
B) It was completely fenced from the rangeland.
C) The ranchers and hunters were all willing to help protect the deer.
D) It was isolated, and the deer had essentially no emigration or immigration.
E) Researchers were able to study every aspect of the issue.
Answer: D
Diff: 1
Objective: 5.5 Characteristics that predict population growth
2) President Roosevelt's actual goal was to ________.
A) improve the range for livestock
B) improve the range for deer
C) preserve and increase the deer
D) preserve the natural environment
E) remove predators
Answer: C
Diff: 1
Objective: 5.5 Characteristics that predict population growth
Read the following scenario and answer the questions below.
Between 1907 and 1923, cattle grazing was greatly reduced, deer hunting was eliminated, and predators
were killed. Over 600 cougars, 11 wolves (most had already been killed in the 1800s), and 3,000 coyotes
were trapped or shot. In response, the deer herd began to increase. By 1915, the deer were estimated at
25,000; by 1920 at 50,000; and by 1923 at approximately 100,000.
3) Which of these graphs shows the Kaibab deer population between 1900 and 1923?
A) a straight line slanting upward, showing a steady increase over time
B) a J-shaped upward curve with a very rapid increase
C) a "sine wave" curving up, down, up, down
D) a rapidly decreasing slope from left to right
E) an S-shaped curve that shows a smooth, rapid increase and then levels off
Answer: B
Diff: 2
Objective: 5.6 Concepts of population ecology
13
4) The removal of the livestock and predators, and the cessation of hunting in 1907 ________.
A) changed the environmental resistance, increasing K for the Kaibab deer
B) changed the environmental resistance, decreasing K for the Kaibab deer
C) removed the limits on immigration, allowing more deer into the area
D) decreased r, allowing more births among Kaibab deer
E) increased r, allowing more births among Kaibab deer
Answer: A
Diff: 3
Objective: 5.6 Concepts of population ecology
5) What is going to happen to the area resources after 1923?
A) The deer herd will have leveled off to a steady state, so the resources will recover.
B) The deer herd will have leveled off to a steady state, but the resources will continue to
be damaged.
C) The deer herd continues to increase, so the resources will continue to be damaged.
D) The deer herd will have begun decreasing, so the resources will recover.
E) As the deer switch to the forage previously used by cattle, the resources will recover.
Answer: C
Diff: 3
Objective: 5.6 Concepts of population ecology
6) The initial population of Kaibab deer in 1906 was about 4,000. In an area of about 800,000
acres, this works out to an average density of one deer per 200 acres. What is the density in
1923?
A) one deer per 20 acres
B) one deer per 800 acres
C) one deer per 80 acres
D) one deer per 8 acres
E) one deer per 0.8 acres
Answer: D
Diff: 2
Objective: 5.6 Concepts of population ecology
7) Mule deer such as the Kaibab population can live 10 to 25 years. In 1920, an age structure
diagram of the Kaibab deer population would ________.
A) look like an inverted triangle, very wide at the top and narrow at the bottom
B) look like a narrow inverted triangle, somewhat wide at the top and narrow at the
bottom
C) be almost the same size from bottom to top, tapering slightly at the top
D) look like a narrow triangle, somewhat wide at the bottom and narrow at the top
E) look like a wide triangle, very wide at the bottom and narrow at the top
Answer: E
Diff: 2
Objective: 5.6 Concepts of population ecology
14