Which of the following statements about speciation is correct?
A. Natural selection chooses the reproductive barriers for populations.
B. When reunited, two allopatric populations will interbreed freely if speciation has occurred.
C. It always takes millions of years for speciation to occur.
D. The goal of natural selection is speciation.
E. Speciation is a basis for understanding macroevolution.

E

Which of the following is the first step in allopatric speciation?
A. hybridization
B. polyploidy
C. formation of a reproductive barrier
D. genetic drift
E. geographic isolation

E

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

E

The question refers to the following description.

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

Which type of reproductive isolation operates to keep the mosquitofish isolated, even when fish from different ponds are reunited in the same body of water?
A. habitat isolation
B. behavioral isolation
C. gametic isolation
D. temporal isolation
E. mechanical isolation

B

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

A

Sympatric speciation is _____.
A. the process by which most animal species have evolved
B. the emergence of many species from a single ancestor
C. initiated by the appearance of a geographic barrier
D. especially important in the evolution of island species
E. the appearance of a new species in the same area as the parent population

E

Hybrid zones provide an opportunity to investigate _____.
A. polyploidy
B. allopatric speciation
C. the evolution of reproductive isolation
D. mutations
E. punctuated equilibrium

C

Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be
A. 28.
B. 16.
C. 12.
D. 56.
E. 14.

A

Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification?
A. The two forms have many genes in common.
B. The two forms live in similar habitats.
C. The two forms interbreed often in nature, and their offspring have good survival and reproduction.
D. The two forms have similar food requirements.
E. The two forms are very similar in coloration.

C

In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago.

In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (15), with 1 being the shallowest.
The Panama Canal was completed in 1914, and its depth is about 50 feet. After 1914, snapping shrimp species from which habitats should be most likely to form hybrids as the result of the canal?

A. A5 and B5
B. A3 and B3
C/ A1 and B1
D. either A1 and A2, or B1 and B2
E. A1A3 and B1B3 have equal likelihoods of harboring snapping shrimp species that can hybridize.

C

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. 4, 1, 2, 3
C. 2, 1, 4, 3
D. 2, 4, 1, 3
E. 4, 2, 1, 3

D

In Europe, there is a long narrow hybrid zone, shown in red on the map, between the high-altitude habitat of the yellow-bellied toad and the lowland habitat of the fire-bellied toad. Despite this, there is little gene flow between the two species. Select the correct explanation.
A. Hybrids have poor survival and reproduction and thus produce few viable offspring with members of either parent species.
B. Toads mate only with their own kind in order to avoid producing unhealthy hybrid young.
C. Yellow-bellied toads and fire-bellied toads are two different species.

A

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. 2 and 4
B. 2 and 3
C. 1 and 4
D. 1 and 3

A

A hybrid zone is properly defined as
A/ a zone that includes the intermediate portion of a cline.
B. a zone that features a gradual change in species composition where two neighboring ecosystems border each other.
C. an area where members of two closely related species intermingle, but experience no gene flow.
D. an area where two closely related species' ranges overlap.
E. an area where mating occurs between members of two closely related species, producing viable offspring.

E

According to the concept of punctuated equilibrium,
A. given enough time, most existing species will gradually give rise to new species.
B. transitional fossils, intermediate between newer species and their parent species, should be abundant.
C. natural selection is unimportant as a mechanism of evolution.
D. a new species accumulates most of its unique features as it comes into existence.
E. evolution of new species features long periods during which changes are occurring, interspersed with short periods of equilibrium, or stasis.

D

The question refers to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change.
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. Z; shared a common ancestor with X most recently, and arose in the same fashion as X
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. V; shared a common ancestor with X most recently
E. This tree does not provide enough information to answer this question.

D

The question refers to the following description.

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

Which two of the following have operated to increase divergence between mosquitofish populations on Andros?
1. improved gene flow
2. bottleneck effect
3. sexual selection
4. founder effect
5. natural selection

A. 3 and 4
B. 2 and 4
C. 2 and 3
D. 1 and 3
E. 3 and 5

E

Which of the following factors would not contribute to allopatric speciation?
A. The isolated population is exposed to different selection pressures than the ancestral population.
B. The separated population is small, and genetic drift occurs.
C. Gene flow between the two populations is extensive.
D. Different mutations begin to distinguish the gene pools of the separated populations.
E. A population becomes geographically isolated from the parent population.

C

The next few questions refer to the following description.

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago.

If the low number of hybrid flies in the hybrid zone, relative to the number of D. santomea flies there, is due to the fact that hybrids are poorly adapted to conditions in the hybrid zone, and if fewer hybrid flies are produced with the passage of time, these conditions will most likely lead to
A. stability.
B. reinforcement.
C. fusion.
D. further speciation events.

B

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. ecological
C. morphological
D. phylogenetic

C

Which of these should decline in hybrid zones where reinforcement is occurring?
A. the genetic distinctness of two gene pools
B. hybrid sterility
C. mutation rate
D. speciation
E. gene flow between distinct gene pools

E

The original habitat of the North American maggot fly, Rhagoletis pomonella, was native hawthorn trees. About 200 years ago, some populations colonized newly introduced apple trees. The two populations are still classified as subspecies, but sympatric speciation is under way. What has contributed to incipient speciation in the maggot fly?
A. Because apples mature more quickly than hawthorn fruit, the apple-feeding flies have been selected for more rapid development.
B. Maggot flies that feed and lay eggs on apples have gradually become adapted to this fruit.
C. Apple maggot flies try to avoid mating with hawthorn maggot flies.

A

Two animals are considered members of different species if they _____.
A. live in different habitats
B. cannot mate and produce viable, fertile offspring
C. look different
D. are geographically isolated
E. are members of different populations

B

What is the most important factor that holds a gene pool of a species together and prevents speciation?
A. behavioral isolation
B. hybridization
C. gene flow
D. prezygotic barriers
E. sexual selection

C

Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?
A. phylogenetic
B. morphological
C. ecological
D. biological

D

The difference between geographic isolation and habitat differentiation is the
A. amount of genetic variation that occurs among two gene pools as speciation occurs.
B. the ploidy of the two populations as speciation occurs.
C. relative locations of two populations as speciation occurs.
D. speed (tempo) at which two populations undergo speciation.
E. identity of the phylogenetic kingdom or domain in which these phenomena occur.

C

The question refers to the following description.

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago.

If a speciation event occurred on Sao Tomé, producing D. santomea from a parent colony of D. yakuba, then which terms apply?
I. macroevolution
II allopatric speciation
III. sympatric speciation
A. I only
B. II only
C. I and II
D. I and III

D

Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent?
A. habitat isolation
B. postzygotic barriers
C. gametic isolation
D. behavioral isolation
E. temporal isolation

D

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. biological and phylogenetic
B. biological and morphological
C. morphological and phylogenetic
D. ecological and morphological
E. ecological and phylogenetic

A

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. reduced hybrid viability
B. behavioral isolation
C. hybrid breakdown
D. mechanical isolation

D

According to the _____ model, evolution occurs in spurts; species evolve relatively rapidly then remain unchanged for long periods.
A. punctuated equilibrium
B. adaptive radiation
C. gradualist
D. geographic isolation
E. nondisjunction

A

In a hypothetical situation, the National Park Service, which administers Grand Canyon National Park in Arizona, builds a footbridge over the Colorado River at the bottom of the canyon. The footbridge permits migration to occur between populations of two closely related antelope squirrels. Previously, one type of squirrel had been restricted to the terrain south of the river, and the other type had been restricted to terrain on the north side of the river. Immediately before and ten years after the bridge's completion, researchers collected ten antelope squirrels from both sides of the river, took blood samples, and collected frequencies of alleles unique to the two types of antelope squirrels (see the following graphs).
The data in the previous graphs indicate that
A.some northern squirrels migrated south, but no southern squirrels migrated north across the bridge.
B. gene flow occurred from one type of squirrel into the gene pool of the other type of squirrel.
C. two-way migration of squirrels occurred across the bridge, but without hybridization.
D. there was no migration between the two squirrel populations after the bridge was completed.
E. a hybrid zone was established after the completion of the bridge.

C

Select the correct statement describing sympatric speciation.
A. Sympatric speciation can occur in a single generation.
B. Sympatric speciation is always initiated by geographic isolation of two populations.
C. Sympatric speciation has never been observed in nature.

A

Theoretically, the production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) should
A. eventually result in the formation of a single species from the two parental species.
B. weaken the intrinsic reproductive barriers between horses and donkeys.
C. strengthen postzygotic barriers between horses and donkeys.
D. cause convergent evolution.
E. result in the extinction of one of the two parental species.

C

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. hybrid breakdown
B. mechanical isolation
C. gametic isolation
D. reduced hybrid fertility
E. habitat isolation

E

The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and
A. a decreasing number of viable, fertile hybrids is produced over the course of generations.
B. an increasing number of viable, fertile hybrids is produced over the course of generations.
C. the hybrid zone is inhospitable to hybrid survival.
D. their chromosomes are no longer homologous enough to permit meiosis.
E. a constant number of viable, fertile hybrids is produced over the course of generations.

B

The question refers to the following description.

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

If one builds a canal linking a predator-rich pond to a predator-poor pond, then what type(s) of selection should subsequently be most expected among the mosquitofish in the original predator-rich pond, and what type(s) should be most expected among the mosquitofish in the formerly predator-poor pond?
A. less-intense disruptive selection; more-intense disruptive selection
B. stabilizing selection; stabilizing selection
C. less-intense directional selection; more-intense directional selection
D. stabilizing selection; directional selection

C

The question refers to the following description.

In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.

Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?
A. The rise of the land bridge was accompanied by much volcanic activity. Volcanic ash contains heavy metals, which are known mutagens. Ash fall caused high levels of heavy metals in the ocean sediments underlying the deep water, resulting in accelerated mutation rates and faster divergence in deepwater shrimp.
B. Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deepwater shrimp.
C. They have been geographically isolated from each other for a longer time.
D. Fresh water entering the ocean from tHe canal is both less dense and cloudier than seawater. The cloudy fresh water interferes with the ability of shallow-water shrimp to locate mating partners, which reduces the frequency of mating, thereby slowing the introduction of genetic variation.

C

According to the punctuated equilibria model,
A. most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species.
B. speciation is usually due to a single mutation.
C. given enough time, most existing species will branch gradually into new species.
D. natural selection is unimportant as a mechanism of evolution.
E. most evolution occurs in sympatric populations.

A

Suppose that a group of male pied flycatchers migrated from a region where there were no collared flycatchers to a region where both species were present (see Figure 24.15 in your textbook). Assuming events like this are very rare, which of the following scenarios is least likely?
A. Pied females would rarely mate with collared males.
B. The frequency of hybrid offspring would decrease.
C. The frequency of hybrid offspring would increase.
D. Migrant males would mate with collared females more often than with pied females.
E. Migrant pied males would produce fewer offspring than would resident pied males.

B

According to the phylogenetic species concept, what is a species?
A. a clone of genetically identical organisms
B. a set of organisms with a unique genetic history
C. a population with a distinct fossil record
D. a population that is physically able to mate even if there are no offspring or the offspring are infertile
E. a population that interbreeds and produces fertile offspring

B

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. introduction of a new predator.
B. pollution.
C. sexual selection.
D. habitat differentiation.
E. polyploidy.

C

The question refers to the following description.

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago.

Which of the following reduces gene flow between the gene pools of the two species on Sao Tomé, despite the existence of hybrids?
A. a geographic barrier
B. hybrid inviability
C. temporal isolation
D. hybrid sterility
E. hybrid breakdown

D

What does the biological species concept use as the primary criterion for determining species boundaries?
A. niche differences
B. gene flow
C. morphological similarity
D. geographic isolation
E. molecular (DNA, RNA, protein) similarit

B

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

C

What is true of the flightless cormorants of the Galápagos Islands?
A. They are close relatives of flightless cormorants from the Americas.
B. They are descendants of the same common ancestor that gave rise to the unique finches of these islands.
C. Flightless cormorants on one island have restricted gene flow with those on other islands, which could someday lead to a macroevolutionary event.
D. 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.
E. Their DNA has low levels of sequence homology with the DNA of flying American cormorants.

C

The question refers to the following description.

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago.

Using only the information provided in the paragraph, which of the following is the best initial hypothesis for how D. santomea descended from D. yakuba?
A. sexual selection
B. allopolyploidy
C. autopolyploidy
D. geographic isolation
E. habitat differentiation

E

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago.

The observation that island D. yakuba are more closely related to mainland D. yakuba than island D. yakuba are to D. santomea is best explained by proposing that D. santomea
A. descended from an original colony of D. yakuba, of which there are no surviving members. The current island D. yakuba represent a second colonization event from elsewhere.
B. descended from a now-extinct, non-African fruit fly.
C. arrived on the island before D. yakuba.
D. descended from a single colony of D. yakuba, which had been introduced from elsewhere, with no subsequent colonization events.

A

The question refers to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change.
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. V and W shared a common ancestor more recently than any of the other species.
D. 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.
E. A single clade (i.e., a group of species that share a common ancestor) can exhibit both gradualism and punctuated equilibri

E

What is true of macroevolution?
A/ It is defined as the evolution of microscopic organisms into organisms that can be seen with the naked eye.
B. It is evolution above the species level.
C. It is the same as microevolution, but includes the origin of new species.
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.

B

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

The predatory fish rely on visual cues and speed to capture mosquitofish. Mosquitofish rely on speed and visual cues to avoid the predatory fish. Which adaptation(s) might help the predators survive in ponds that are home to faster mosquitofish?
1. directional selection for increased speed
2. stabilizing selection for speed that matches that of the mosquitofish
3. change in hunting behavior that replaces reliance on visual cues with reliance on tactile cues, which can be used to hunt at night
4. change in hunting behavior that eliminates speed in favor of better camouflage, which permits an ambush strategy
A. 1 only
B. 2 only
C. either 1 or 3
D. either 2 or 3
E. 1, 3, or 4

E

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

B

Speciation
A. must begin with the geographic isolation of a small, frontier population.
B. occurs at such a slow pace that no one has ever observed the emergence of new species.
C. and macroevolution are synonymous.
D. can involve changes to a single gene.
E. occurs only by the accumulation of genetic change over vast expanses of time.

D

Adaptive radiations on archipelagos (island chains) represent some of the best-understood speciation events. Why is an ancestral species more likely to give rise to multiple descendent species on an archipelago than on an equal-sized area of mainland?
A. Populations on nearby islands are more likely to be genetically isolated than populations that are equally close to one another on the mainland.
B. By chance, different species will colonize different islands in a chain.
C. Favorable mutations are more likely to arise on an archipelago as populations try to adapt to conditions on their specific island.

A

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 breakdown
B. the prezygotic barrier called hybrid sterility
C. the postzygotic barrier called hybrid inviability
D. gametic isolation

C

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. The alleles' heterozygosity should be higher among the hybrid toads there.
C. Their allele frequency should be nearly the same as the allele frequencies in toad populations distant from the hybrid zone.
D. Their allele frequency on one edge of the hybrid zone should roughly equal their frequency on the opposite edge of the hybrid zone.

B

In order for speciation to occur, what must be true?
A/ Large numbers of genes that affect numerous phenotypic traits must change.
B. Large numbers of genes that affect a single phenotypic trait must change.
C. The number of chromosomes in the gene pool must change.
D. At least one gene, affecting at least one phenotypic trait, must change.
E. Changes to centromere location or chromosome size must occur within the gene pool.

D

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. sympatric speciation; allopolyploidy
B. sympatric speciation; sexual selection
C. sympatric speciation; habitat differentiation
D. allopatric speciation; ecological isolation
E. allopatric speciation; behavioral isolation

C

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. ecological
B. morphological
C. biological
D. phylogenetic

C

Which of these is an example of temporal isolation?
A. One species is found only in New York, the other only in London.
B. One is a type of primate, the other is a type of marsupial.
C. One species performs a specific courtship dance. the other species does not.
D. One species is nocturnal, and the other species is not.
E. The average weight of the individuals in one species is 45 kg; in the other species the average is 290 kg.

D

In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago.

In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (15), with 1 being the shallowest.

There are currently two, large, permanent bridges that span the Panama Canal. The bridges are about 8 miles apart. If snapping shrimp avoid swimming at night and avoid swimming under shadows, then what do these bridges represent for the snapping shrimp?
A. sources of a hybrid zone between the two bridges
B. sources of refuge
C. geographic barriers
D. sources for increased gene flow

C

The most likely explanation for the recent decline in cichlid species diversity in Lake Victoria is
A/ stability.
B. reinforcement.
C. geographic isolation.
D. fusion.
E. polyploidy.

D

The largest unit within which gene flow can readily occur is a
A. species.
B. genus.
C. population.
D. hybrid.
E. phylum.

A