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

biological

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

morphological

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

habitat isolation

Rank the following from most general to most specific:
1. gametic isolation
2. reproductive isolating mechanism
3. sperm–egg incompatibility in sea urchins
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

2, 4, 1, 3

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

the postzygotic barrier called hybrid inviability

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.

strengthen postzygotic barriers between horses and donkeys.

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

biological and phylogenetic

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

gene flow

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

1 and 2

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

1 through 4

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.

relative locations of two populations as speciation occurs.

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

2 and 4

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

sympatric speciation; habitat differentiation

The origin of a new plant species by hybridization, coupled with accidents during cell
division, is an example of
A) allopatric speciation.
B) sympatric speciation.
C) autopolyploidy.
D) habitat selection.

sympatric speciation.

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.

sexual selection.

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.

D) an increasing number of viable, fertile hybrids is produced over the course of generations.

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.

an area where mating occurs between members of two closely related species, producing
viable offspring.

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

gene flow between distinct gene pools

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.

fusion.

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.

The alleles' heterozygosity should be higher among the hybrid toads there.

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.

speciation occurred rapidly in geologic time.

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 gradually give rise to 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.

a new species accumulates most of its unique features as it comes into existence.

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

mechanical isolation

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 macroevolution are synonymous.
E) can involve changes to a single gene.

can involve changes to a single gene.

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.

At least one gene, affecting at least one phenotypic trait, must change.