Campbell’s Biology, 9e (Reece et al.)
Chapter 24 The Origin of Species
The major changes to the Test Bank for Chapter 24 are two sets of scenario questions. The first of these
deals with the adaptation of mosquitofish on the Bahamian Island of Andros. The second deals with
reproductive isolation that occurred to marine species on either side of the Isthmus of Panama as it arose
from the ocean floor.
Multiple-Choice Questions
1) What is true of macroevolution?
A) It is the same as microevolution, but includes the origin of new species.
B) It is evolution above the species level.
C) It is defined as the evolution of microscopic organisms into organisms that can be seen with the
naked eye.
D) It is defined as a change in allele or gene frequency over the course of many generations.
E) It is the conceptual link between irritability and adaptation.
2) What is true of the flightless cormorants of the Galápagos Islands?
A) They are descendants of the same common ancestor that gave rise to the unique finches of these
islands.
B) They are close relatives of flightless cormorants from the Americas.
C) If they are still able to breed successfully with flying cormorants, it would probably be with North
American cormorants, rather than with South American cormorants.
D) Flightless cormorants on one island have restricted gene flow with those on other islands, which
could someday lead to a macroevolutionary event.
E) Their DNA has low levels of sequence homology with the DNA of flying American cormorants.
3) Which of the following statements about species, as defined by the biological species concept, is (are)
correct?
I. Biological species are defined by reproductive isolation.
II. Biological species are the model used for grouping extinct forms of life.
III. The biological species is the largest unit of population in which successful interbreeding is possible.
A) I and II
B) I and III
C) II and III
D) I, II, and III
4) Which of the various species concepts distinguishes two species based on the degree of genetic
exchange between their gene pools?
A) phylogenetic
B) ecological
C) biological
D) morphological
5) There is still some controversy among biologists about whether Neanderthals should be placed within
the same species as modern humans or into a separate species of their own. Most DNA sequence data
analyzed so far indicate that there was probably little or no gene flow between Neanderthals and Homo
sapiens. Which species concept is most applicable in this example?
A) phylogenetic
B) ecological
C) morphological
D) biological
6) You are confronted with a box of preserved grasshoppers of various species that are new to science
and have not been described. Your assignment is to separate them into species. There is no
accompanying information as to where or when they were collected. Which species concept will you
have to use?
A) biological
B) phylogenetic
C) ecological
D) morphological
7) Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are
fertile. This kind of isolation is most similar to which of the following reproductive isolating
mechanisms?
A) reduced hybrid fertility
B) hybrid breakdown
C) mechanical isolation
D) habitat isolation
E) gametic isolation
8) Rank the following from most general to most specific:
1. gametic isolation
2. reproductive isolating mechanism
3. pollen-stigma incompatibility
4. prezygotic isolating mechanism
A) 2, 3, 1, 4
B) 2, 4, 1, 3
C) 4, 1, 2, 3
D) 4, 2, 1, 3
E) 2, 1, 4, 3
9) Two species of frogs belonging to the same genus occasionally mate, but the offspring fail to develop
and hatch. What is the mechanism for keeping the two frog species separate?
A) the postzygotic barrier called hybrid inviability
B) the postzygotic barrier called hybrid breakdown
C) the prezygotic barrier called hybrid sterility
D) gametic isolation
10) Theoretically, the production of sterile mules by interbreeding between female horses (mares) and
male donkeys (jacks) should
A) result in the extinction of one of the two parental species.
B) cause convergent evolution.
C) strengthen postzygotic barriers between horses and donkeys.
D) weaken the intrinsic reproductive barriers between horses and donkeys.
E) eventually result in the formation of a single species from the two parental species.
11) When male horses (stallions) and female donkeys (jennets) mate, they produce a sterile hybrid called
a hinny. Hinnies occur much less frequently than do mules, but are just as healthy and robust as mules.
Logically, which of the following best accounts for the relative rarity of hinnies, and what kind of
prezygotic isolating mechanism is at work here?
A) Most hinnies die during fetal development; reduced hybrid viability.
B) Most hinnies die soon after being born; hybrid breakdown.
C) Most hinnies are reproductively sterile; reduced hybrid fertility.
D) Stallions and jennets are choosier about their mating partners than are mares and jacks; behavioral
isolation.
E) Stallions and jennets are choosier about their mating partners than are mares and jacks; gametic
isolation.
12) Dogs (Canis lupus familiaris) and gray wolves (Canis lupus) can interbreed to produce viable, fertile
offspring. These species shared a common ancestor recently (in geologic time) and have a high degree
of genetic similarity, although their anatomies vary widely. Judging from this evidence, which two
species concepts are most likely to place dogs and wolves together into a single species?
A) ecological and morphological
B) ecological and phylogenetic
C) morphological and phylogenetic
D) biological and morphological
E) biological and phylogenetic
13) Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have
overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to
germinate and make pollen tubes on female ovules (which contain egg cells) of the other species, then
which of these terms are applicable?
1. sympatric species
2. prezygotic isolation
3. postzygotic isolation
4. allopatric species
5. habitat isolation
6. reduced hybrid fertility
A) 1 and 2
B) 2 and 4
C) 1, 3, and 6
D) 2, 4, and 5
E) 1, 2, 5, and 6
14) Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have
overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to
germinate and make pollen tubes on female ovules (which contain egg cells) of the other species, then
which of these terms is applicable?
A) behavioral isolation
B) mechanical isolation
C) hybrid breakdown
D) reduced hybrid viability
15) What does the biological species concept use as the primary criterion for determining species
boundaries?
A) geographic isolation
B) niche differences
C) gene flow
D) morphological similarity
E) molecular (DNA, RNA, protein) similarity
16) In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. In rangelands
of the western United States, pronghorns and cattle often associate with one another. If some of these
fleas develop a strong preference for cattle blood and mate only with other fleas that prefer cattle blood,
then over time which of these should occur, if the host mammal can be considered as the fleas’ habitat?
1. reproductive isolation
2. sympatric speciation
3. habitat isolation
4. prezygotic barriers
A) 1 only
B) 2 and 3
C) 1, 2, and 3
D) 2, 3, and 4
E) 1 through 4
17) Two closely related populations of mice have been separated for many generations by a river.
Climatic change causes the river to dry up, thereby bringing the mice populations back into contact in a
zone of overlap. Which of the following is not a possible outcome when they meet?
A) They interbreed freely and produce fertile hybrid offspring.
B) They no longer attempt to interbreed.
C) They interbreed in the region of overlap, producing an inferior hybrid. Subsequent interbreeding
between inferior hybrids produces progressively superior hybrids over several generations.
D) They remain separate in the extremes of their ranges but develop a persistent hybrid zone in the area
of overlap.
E) They interbreed in the region of overlap, but produce sterile offspring.
18) The difference between geographic isolation and habitat differentiation is the
A) relative locations of two populations as speciation occurs.
B) speed (tempo) at which two populations undergo speciation.
C) amount of genetic variation that occurs among two gene pools as speciation occurs.
D) identity of the phylogenetic kingdom or domain in which these phenomena occur.
E) the ploidy of the two populations as speciation occurs.
19) Among known plant species, which of these have been the two most commonly occurring
phenomena that have led to the origin of new species?
1. allopatric speciation
2. sympatric speciation
3. sexual selection
4. polyploidy
A) 1 and 3
B) 1 and 4
C) 2 and 3
D) 2 and 4
20) Beetle pollinators of a particular plant are attracted to its flowers’ bright orange color. The beetles
not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant
with red flowers becomes more common with the passage of time. A particular variant of the beetle
prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each
other to such an extent that interbreeding is no longer possible. What kind of speciation has occurred in
this example, and what has driven it?
A) allopatric speciation; ecological isolation
B) sympatric speciation; habitat differentiation
C) allopatric speciation; behavioral isolation
D) sympatric speciation; sexual selection
E) sympatric speciation; allopolyploidy
21) The origin of a new plant species by hybridization, coupled with accidents during nuclear division,
is an example of
A) allopatric speciation.
B) sympatric speciation.
C) autopolyploidy.
D) habitat selection.
22) The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two
populations meet again and
A) their chromosomes are no longer homologous enough to permit meiosis.
B) a constant number of viable, fertile hybrids is produced over the course of generations.
C) the hybrid zone is inhospitable to hybrid survival.
D) an increasing number of viable, fertile hybrids is produced over the course of generations.
E) a decreasing number of viable, fertile hybrids is produced over the course of generations.
23) A hybrid zone is properly defined as
A) an area where two closely related species’ ranges overlap.
B) an area where mating occurs between members of two closely related species, producing viable
offspring.
C) a zone that features a gradual change in species composition where two neighboring ecosystems
border each other.
D) a zone that includes the intermediate portion of a cline.
E) an area where members of two closely related species intermingle, but experience no gene flow.
24) Which of these should decline in hybrid zones where reinforcement is occurring?
A) gene flow between distinct gene pools
B) speciation
C) the genetic distinctness of two gene pools
D) mutation rate
E) hybrid sterility
25) The most likely explanation for the high rate of sympatric speciation that apparently existed among
the cichlids of Lake Victoria in the past is
A) sexual selection.
B) habitat differentiation.
C) polyploidy.
D) pollution.
E) introduction of a new predator.
26) The most likely explanation for the recent decline in cichlid species diversity in Lake Victoria is
A) reinforcement.
B) fusion.
C) stability.
D) geographic isolation.
E) polyploidy.
27) A narrow hybrid zone separates the toad species Bombina bombina and Bombina variegata. What is
true of those alleles that are unique to the parental species?
A) Such alleles should be absent.
B) Their allele frequency should be nearly the same as the allele frequencies in toad populations distant
from the hybrid zone.
C) The alleles’ heterozygosity should be higher among the hybrid toads there.
D) Their allele frequency on one edge of the hybrid zone should roughly equal their frequency on the
opposite edge of the hybrid zone.
28) According to the concept of punctuated equilibrium, the “sudden” appearance of a new species in the
fossil record means that
A) the species is now extinct.
B) speciation occurred instantaneously.
C) speciation occurred in one generation.
D) speciation occurred rapidly in geologic time.
E) the species will consequently have a relatively short existence, compared with other species.
29) According to the concept of punctuated equilibrium,
A) natural selection is unimportant as a mechanism of evolution.
B) given enough time, most existing species will branch gradually into new species.
C) a new species accumulates most of its unique features as it comes into existence.
D) evolution of new species features long periods during which changes are occurring, interspersed with
short periods of equilibrium, or stasis.
E) transitional fossils, intermediate between newer species and their parent species, should be abundant.
30) Speciation
A) occurs at such a slow pace that no one has ever observed the emergence of new species.
B) occurs only by the accumulation of genetic change over vast expanses of time.
C) must begin with the geographic isolation of a small, frontier population.
D) and microevolution are synonymous.
E) can involve changes to a single gene.
31) Which of the following statements about speciation is correct?
A) The goal of natural selection is speciation.
B) When reunited, two allopatric populations will interbreed freely if speciation has occurred.
C) Natural selection chooses the reproductive barriers for populations.
D) Prezygotic reproductive barriers usually evolve before postzygotic barriers.
E) Speciation is a basis for understanding macroevolution.
32) In order for speciation to occur, what must be true?
A) The number of chromosomes in the gene pool must change.
B) Changes to centromere location or chromosome size must occur within the gene pool.
C) Large numbers of genes that affect a single phenotypic trait must change.
D) Large numbers of genes that affect numerous phenotypic traits must change.
E) At least one gene, affecting at least one phenotypic trait, must change.
Art Questions
The next few questions refer to the following evolutionary tree, whose horizontal axis represents time
(present time is on the far right) and whose vertical axis represents morphological change.
33) Which species is most closely related to species W?
A) V is most closely related to species W.
B) X is most closely related to species W.
C) Y and Z are equally closely related to W.
D) It is not possible to say from this tree.
34) Which species is least expected to have a good record of transitional fossils; in other words, which
species’ fossils, if present at all, are expected only in relatively superficial (i.e., shallow) strata?
A) V
B) W
C) X
D) Y
E) Z
35) Which of these five species originated earliest and appeared suddenly in the fossil record?
A) V
B) W
C) X
D) Y
E) Z
36) Which conclusion can be drawn from this evolutionary tree?
A) Gradualistic speciation and speciation involving punctuated equilibrium are mutually exclusive
concepts; only one of them can occur.
B) Eldredge and Gould would deny that the lineages labeled X, Y, and Z could represent true species.
C) Assuming that the tip of each line represents a species, there are five extant (i.e., not extinct) species
resulting from the earliest common ancestor.
D) A single clade (i.e., a group of species that share a common ancestor) can exhibit both gradualism
and punctuated equilibrium.
E) V and W shared a common ancestor more recently than any of the other species.
37) Which of these five species is the extant (i.e., not extinct) species that is most closely related to
species X, and why is this so?
A) V; shared a common ancestor with X most recently
B) W; shared a common ancestor with X most recently
C) Y; arose in the same fashion (i.e., at the same tempo) as X
D) Z; shared a common ancestor with X most recently, and arose in the same fashion as X
E) This tree does not provide enough information to answer this question.