AP Biology : Understanding Sympatric and Allopatric Speciation

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #11 : Speciation

Which of the following describes how parapatric speciation differs from peripatric speciation?

Possible Answers:

There is no contact between the two diverging populations in parapatric speciation

There can be contact between the two diverging populations in parapatric speciation

Parapatric speciation and peripatric speciation do not differ

Parapatric speciation is a subgroup of peripatric speciation

Correct answer:

There can be contact between the two diverging populations in parapatric speciation

Explanation:

In parapatric speciation, the two diverging species still have geographic contact but there is selection against genetic exchange due to a heterozygote disadvantage. Parapatric speciation differs from peripatric speciation because there is no contact between diverging populations in peripatric speciation.

Example Question #11 : Speciation

Which of the following best defines sympatric speciation?

Possible Answers:

A population divides into two adjacent niches with contact and minimal genetic exchange

Isolated peripheral populations cease genetic exchange

Formation of two distinct species within the same geographic location

Populations diverge due to geographic location

Correct answer:

Formation of two distinct species within the same geographic location

Explanation:

In cases of sympatric speciation, two distinct species diverge from the same population within the same geographic location.

Example Question #11 : Speciation

Which of the following is false of sympatric populations?

Possible Answers:

Sympatric populations diverge due to geographic isolation 

Sympatric populations are geographically overlapping 

Sympatric populations show differences in body structure 

Sympatric populations may form hybrids 

Sympatric populations diverge due to behavioral isolation

Correct answer:

Sympatric populations diverge due to geographic isolation 

Explanation:

Allopatric literally means “other fatherland,” meaning that populations are geographically separate. Because populations are separate, they may use similar resources and be similar in structure. Allopatric populations come about due to geographic isolation, rather than behavioral isolation. Sympatric means “same fatherland,” meaning that populations are geographically overlapping and diverge due to behavioral isolation. As a result, they may also, show divergence from a common resource and original body structure. Where the two sympatric populations overlap, there is a hybrid zone. The two species may mate and produce hybrid offspring. 

Example Question #11 : Understanding Sympatric And Allopatric Speciation

A population of rabbits lives in a forest in the Southeastern United States. A large group of rabbits is cut off from the population when a six-lane highway is built through the forest. Over many generations, the large group of rabbits begins to develop darker fur in response to the dominant foliage on one side of the highway. When rabbits from the two populations are brought together, they no longer reproduce with each other. What kind of speciation does this represent?

Possible Answers:

Sympatric

Allopatric

Temporal

Founder effect

Correct answer:

Allopatric

Explanation:

Geographic speciation can be broadly divided into two categories: allopatric or sympatric. Sympatric speciations occurs when species diverge while living in the same geographic habitat. Allopatric speciation occurs when two populations of a species become separated (in this case by a highway), and over time become separate species.

Example Question #11 : Understanding Sympatric And Allopatric Speciation

Which of the following is an example of sympatric speciation?

Possible Answers:

None of these

A population of butterflies is split when a housing development is built, splitting their habitat in two. Butterflies from each group rarely go to the opposite side of the development, so opportunities for breeding between the groups are very limited.

A population of bears prefers red berries. At some point, part of the population develops a preference for blue berries. Eventually, the two groups no longer interact to the point that they no longer breed.

Two populations of mice compete for the same resources in a forrest. After several years, the two populations of mice begin mating with one another.

Correct answer:

A population of bears prefers red berries. At some point, part of the population develops a preference for blue berries. Eventually, the two groups no longer interact to the point that they no longer breed.

Explanation:

Sympatric speciation, which most biologists agree is very uncommon, occurs when a population lives in the same habitat but diverges into two species. In this case, the bears occupied the same area but became isolated based on their diet. Note that for this to occur, selection on diet preference would need to be very strong.

Example Question #11 : Understanding Sympatric And Allopatric Speciation

There was once a population on planet M311, called the Freg, who lived on a planet not unlike Earth. At the height of the Fregs technology and evolution, a collection of asteroids bombarded the planet and the devastation was so great that the planet was split in two, as was the Freg population. Much of the Freg population died, but many still survived on both pieces of M311.

As time progressed following the catastrophe, the genetic structure of the Freg populations began to differ from each other since they were no longer reproducing with each other. What is this process called?

Possible Answers:

Genetic conversion

Sympatric speciation

Evolutionary segregation

Allopatric speciation

None of these

Correct answer:

Allopatric speciation

Explanation:

Allopatric speciation is the correct answer. Allopatric speciation is when one species results in two species as a result of environmental barriers. In this instance, the separation of the planet is a physical barrier that leads to the Freg becoming two different species.

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