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. Assuming events like this are very rare, which of the following scenarios is least likely?

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. Assuming events like this are very rare, which of the following scenarios is least likely? 

A) The frequency of hybrid offspring would increase.
B) Migrant pied males would produce fewer offspring than would resident pied males.
C) Pied females would rarely mate with collared males.
D) Migrant males would mate with collared females more often than with pied females.
E) The frequency of hybrid offspring would decrease.



Answer: E

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

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) 12.
B) 14.
C) 16.
D) 28.
E) 56.


Answer: D

Which of the following factors would not contribute to allopatric speciation?

Which of the following factors would not contribute to allopatric speciation? 

A) A population becomes geographically isolated from the parent population.
B) The separated population is small, and genetic drift occurs.
C) The isolated population is exposed to different selection pressures than the ancestral population.
D) Different mutations begin to distinguish the gene pools of the separated populations.
E) Gene flow between the two populations is extensive.



Answer: E

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?

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 interbreed often in nature, and their offspring have good survival and reproduction.
B) The two forms live in similar habitats.
C) The two forms have many genes in common.
D) The two forms have similar food requirements.
E) The two forms are very similar in coloration.



Answer: A

According to the punctuated equilibria model,

According to the punctuated equilibria model,

A) natural selection is unimportant as a mechanism of evolution.
B) given enough time, most existing species will branch gradually into new species.
C) 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.
D) most evolution occurs in sympatric populations.
E) speciation is usually due to a single mutation.



Answer: C

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?

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) temporal isolation
C) behavioral isolation
D) gametic isolation
E) postzygotic barriers




Answer: C

The largest unit within which gene flow can readily occur is a

The largest unit within which gene flow can readily occur is a 

A) population.
B) species.
C) genus.
D) hybrid.
E) phylum.



Answer: 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.

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) 1 and 3
B) 2 and 3
C) 2 and 4
D) 3 and 4
E) 3 and 5


Answer: E

Which type of reproductive isolation operates to keep the mosquito fish isolated, even when fish from different ponds are reunited in the same body of water? 

A) behavioral isolation
B) habitat isolation
C) temporal isolation
D) mechanical isolation
E) gametic isolation

Answer: A

What is the best way to promote fusion between two related populations of mosquitofish, one of which lives in a predator-rich pond, and the other of which lives in a predator-poor pond? 

A) Build a canal linking the two ponds that permits free movement of mosquitofish, but not of predators.
B) Transfer only female mosquitofish from a predator-rich pond to a predator-poor pond.
C) Perform a reciprocal transfer of females between predator-rich and predator-poor ponds.
D) Remove predators from a predator-rich pond and transfer them to a predator-poor pond.

Answer: A

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) stabilizing selection; directional selection
B) stabilizing selection; stabilizing selection
C) less-intense directional selection; more-intense directional selection
D) less-intense disruptive selection; more-intense disruptive selection



Answer: C

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


Answer: 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.

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) hybrid breakdown
B) hybrid inviability
C) hybrid sterility
D) temporal isolation
E) a geographic barrier


Answer: C

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 a now-extinct, non-African fruit fly.
B) arrived on the island before D. yakuba.
C) descended from a single colony of D. yakuba, which had been introduced from elsewhere, with no subsequent colonization events.
D) 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.


Answer: D

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


Answer: D

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) geographic isolation
B) autopolyploidy
C) habitat differentiation
D) sexual selection
E) allopolyploidy



Answer: C

Which of these evolutionary trees represents the situation described in the previous paragraph (Note: Yakuba (I) represents the island population, and yakuba (M) represents the mainland population)? 

A. SEE IMAGE
B. SEE IMAGE
C. SEE IMAGE
D. SEE IMAGE

Answer: A

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) fusion.
B) reinforcement.
C) stability.
D) further speciation events.



Answer: B

In order for speciation to occur, what must be true?

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.



Answer: E

Which of the following statements about speciation is correct?

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.



Answer: E

Speciation 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.

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.


Answer: E

According to the concept of punctuated equilibrium,

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.




Answer: C

According to the concept of punctuated equilibrium, the "sudden" appearance of a new species in the fossil record means that

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.



Answer: D

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 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.



Answer: C

The most likely explanation for the recent decline in cichlid species diversity in Lake Victoria is

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.



Answer: 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

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.



Answer: A

Which of these should decline in hybrid zones where reinforcement is occurring?

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



Answer: A

A hybrid zone is properly defined as

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.



Answer: B

The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and

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.



Answer: D