CHAPTER 23 Flashcards

Which of the following ecological locations has the greatest species diversity?
A) tundra
B) deciduous forests
C) tropical rain forest
D) grasslands
E) islands

Invasive species are introduced by humans to new geographic locations and
A) are successful in colonizing a novel area.
B) spread because they encounter none of their natural predators.
C) All of the choices are correct.
D) can outcompete and displace native species for biotic and abiotic resources.
E) are usually considered pests by ecologists.

Estimates of current rates of extinction
A) indicate that we have reached a state of stable equilibrium in which speciation rates equal
extinction rates.
B) suggest that one-half of all animal and plant species may be gone by the year 2100.
C) indicate that rates may be greater than the mass extinctions at the close of the Cretaceous
period.
D) indicate that only 1% of all of the species that have ever lived on Earth are still alive.
E) suggest that rates of extinction have decreased globally.

Extinction is a natural phenomenon. It is estimated that 99% of all species that ever lived are
now extinct. Why then do we say that we are now experiencing an extinction (loss of
biodiversity) crisis?
A) Humans are ethically responsible for protecting endangered species.
B) Scientists have finally identified most of the species on Earth and are thus able to quantify the
number of species becoming extinct.
C) The current rate of extinction is high and human activities threaten biodiversity at all levels.
D) Humans have greater medical needs than at any other time in history, and many potential
medicinal compounds are being lost as plant species become extinct.
E) Most biodiversity hot spots have been destroyed by recent ecological disasters.

Which of the following provides the best evidence of a biodiversity crisis?
A) the incursion of a non-native species
B) increasing pollution levels
C) decrease in regional productivity
D) high rate of extinction
E) climate change

Although extinction is a natural process, current extinctions are of concern to
environmentalists because
A) more animals than ever before are going extinct.
B) most current extinctions are caused by introduced species.
C) the rate of extinction is higher than background extinction rates.
D) current extinction is primarily affecting plant diversity.
E) None of the options are correct.

Which of the following terms includes all of the others?
A) species diversity
B) biodiversity
C) genetic diversity
D) ecosystem diversity
E) species richness

According to the U.S. Endangered Species Act (ESA), the difference between an endangered
species and a threatened one is that
A) an endangered species is closer to extinction.
B) a threatened species is closer to extinction.
C) threatened species are endangered species outside the U.S. borders.
D) endangered species are mainly tropical.
E) only endangered species are vertebrates.

What term did E. O. Wilson coin for our innate appreciation of wild environments and living
organisms?
A) bioremediation
B) bioethics
C) biophilia
D) biophobia
E) landscape ecology

We should care about loss in biodiversity in the populations of other species because of
A) biophilia.
B) potential loss of medicines and other products yet undiscovered from threatened species.
C) potential loss of genes, some of which may code for proteins useful to humans.
D) the risk to global ecological stability.
E) All of the options are correct.

The most serious consequence of a decrease in global biodiversity would be the
A) increase in global warming and thinning of the ozone layer.
B) potential loss of ecosystem services on which people depend.
C) increase in the abundance and diversity of edge-adapted species.
D) loss of sources of genetic diversity to preserve endangered species.
E) loss of species for use as crops.

Which of the following is the most direct threat to biodiversity?
A) increased levels of atmospheric carbon dioxide
B) the depletion of the ozone layer
C) overexploitation of selected species
D) habitat destruction
E) zoned reserves

According to most conservation biologists, the single greatest threat to global biodiversity is
A) chemical pollution of water and air.
B) stratospheric ozone depletion.
C) overexploitation of certain species.
D) alteration or destruction of the physical habitat.
E) global climate change resulting from a variety of human activities.

What is the biological significance of genetic diversity between populations?
A) Genes for adaptive traits to local conditions make microevolution possible.
B) The population that is most fit would survive by competitive exclusion.
C) Genetic diversity allows for species stability by preventing speciation.
D) Isolated populations become more fit.
E) Diseases and parasites are not spread between separated populations.

Introduced species can have deleterious effects on biological communities by
A) preying on native species.
B) competing with native species for food or light.
C) displacing native species.
D) competing with native species for space or breeding/nesting habitat.
E) All of the options are correct.

Overexploitation encourages extinction and is most likely to affect
A) animals that occupy a broad ecological niche.
B) large animals with low intrinsic reproductive rates.
C) most organisms that live in the oceans.
D) terrestrial organisms more than aquatic organisms.
E) edge-adapted species.

How might the extinction of some Pacific Island bats called "flying foxes" threaten the
survival of over 75% of the tree species in those islands?
A) wetland and riparian
B) open and benthic ocean
C) desert and high alpine
D) taiga and second-growth forests
E) tundra and arctic

Of the following ecosystem types, which have been impacted the most by humans?
A) wetland and riparian
B) open and benthic ocean
C) desert and high alpine
D) taiga and second-growth forests
E) tundra and arctic

The introduction of the brown tree snake in the 1940s to the island of Guam has resulted in
A) eradication of non-native rats and other undesirable/pest species.
B) the extirpation of many of the island's bird and reptile species.
C) a good lesson in biological control.
D) a new species of hybrids from crossbreeding with a native snake species.
E) its failure to compete with native species and its quick elimination from the island.

Which of the following examples poses the greatest potential threat to biodiversity?
A) replanting, after a clear cut, a monoculture of Douglas fir trees on land that consisted of old-
growth Douglas fir, western cedar, and western hemlock
B) allowing previously used farmland to go fallow and begin to fill in with weeds and then
shrubs and saplings
C) trapping and relocating large predators, such as mountain lions, that pose a threat as they
move into areas of relatively dense human populations
D) importing an Asian insect into the United States to control a weed that competes with staple
crops
E) releasing sterilized rainbow trout to boost the sport fishing of a river system that contains
native brook trout

Which of the following is a type of research in which a conservation biologist would be
involved?
A) reestablishing whooping cranes in their former breeding grounds in North Dakota
B) studying species diversity and interaction in the Florida Everglades, past and present
C) studying the population ecology of grizzly bears in Yellowstone National Park
D) determining the effects of hunting white-tailed deer in Vermont
E) All of the options are correct.

Which of the following species was driven to extinction by overexploitation by
hunters/fishermen?
A) African elephant
B) the great auk
C) North American bluefin tuna
D) flying foxes
E) American bison

Which of the following conditions is the most likely indicator of a population in an
extinction vortex?
A) The population is geographically divided into many populations.
B) The species in question is found only in small, stable pockets of its former range.
C) The effective population size of the species falls below 500.
D) Genetic measurements indicate a loss of genetic variation over time.
E) The population is connected only by corridors.

Review the formula for effective population size. Imagine a population of 1,000 small
rodents. Of these, 300 are breeding females, 300 are breeding males, and 400 are nonbreeding
juveniles. What is the effective population size?
A) 1,000
B) 1,200
C) 600
D) 400
E) 300

If the sex ratio in a population is significantly different from 50:50, then which of the
following will always be true?
A) The population will enter the extinction vortex.
B) The genetic variation in the population will increase over time.
C) The genetic variation in the population will decrease over time.
D) The effective population size will be greater than the actual population size.
E) The effective population size will be less than the actual population size.

Which of the following life history traits can potentially influence effective population size
(Ne)?
A) maturation age
B) genetic relatedness among individuals in a population
C) population size
D) gene flow between geographically separated populations
E) All of the options are correct.

The word triage originated during World War I and was first used by French doctors in
prioritizing patients based on the severity of their wounds, because there were more wounded
soldiers in need of urgent care than there were resources to treat them. Conservation biologists
have to make similar determinations with degraded ecosystems. Which of the following is the
most important consideration when it comes to managing for maintenance of biodiversity?

A) identifying large, high-profile vertebrates first, because steps to saving them would be most
recognized by the public
B) determining which species is most important for conserving biodiversity as a whole
C) replanting suitable habitat for fauna
D) assessing the economic costs and the gains for society
E) maintaining optimum size of all populations in the ecosystem

The primary difference between the small-population approach (S-PA) and the declining-
population approach (D-PA) to biodiversity recovery is
A) S-PA is interested in bolstering the genetic diversity of a threatened population rather than the
environmental factors that caused the population's decline.
B) S-PA kicks in for conservation biologists when population numbers fall below 500.
C) D-PA would likely involve bringing together individuals from scattered small populations to
interbreed in order to promote genetic diversity.
D) S-PA would investigate and eliminate all of the human impacts on the habitat of the species
being studied for recovery.
E) D-PA would use recently collected population data to calculate an extinction vortex.

The long-term problem with red-cockaded woodpecker habitat intervention in the
southeastern United States is
A) the only habitat that can support their recovery is large tracts of mature oak forest.
B) the mature pine forests in which they live cannot ever be subjected to forest fire.
C) all of the appropriate red-cockaded woodpecker habitat has already been logged or converted
to agricultural land.
D) the social organization of the red-cockaded woodpecker precludes the dispersal of
reproductive individuals.
E) what habitat remains for the red-cockaded woodpecker does not contain trees suitable for
nest-cavity construction.

Managing southeastern forests specifically for the red-cockaded woodpecker
A) required the growth of a dense understory of trees and shrubs.
B) contributed to greater abundance and diversity of other forest bird species.
C) caused other species of songbird to decline.
D) involved strict fire-suppression measures.
E) involved the creation of fragmented forest habitat.

Which of the following is true about the current research regarding forest fragmentation?
A) Fragmented forests support a greater biodiversity because they result in the combination of
forest-edge species and forest-interior species.
B) Fragmented forests support a lesser biodiversity because the forested-adapted species leave,
and only the edge and open-field species can occupy fragmented forests.
C) Fragmented forests are the goal of conservation biologists who design wildlife preserves.
D) Harvesting timber that results in forest fragmentation results in less soil erosion.
E) The disturbance of timber extraction causes the species diversity to increase because of the
new habitats created.

According to the small-population approach, what would be the best strategy for saving a
population from extirpation?
A) determining the minimum viable population size by taking into account the effective
population size
B) establishing a nature reserve to protect its habitat
C) introducing individuals from other populations to increase genetic variation
D) determining and remedying the cause of its decline
E) reducing the population size of its predators and competitors

Relatively small geographic areas with high concentrations of endemic species and a large
number of endangered and threatened species are known as
A) endemic sinks.
B) critical communities.
C) biodiversity hot spots.
D) endemic metapopulations.
E) bottlenecks.

How is habitat fragmentation related to biodiversity loss?
A) Less carbon dioxide is absorbed by plants in fragmented habitats.
B) In fragmented habitats, more soil erosion takes place.
C) Populations of organisms in fragments are smaller, and thus more susceptible to extinction.
D) Animals are forced out of smaller habitat fragments.
E) Fragments generate silt that negatively affects sensitive river and stream organisms.