GRE Subject Test: Biology : Understanding Types of Speciation

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

Example Question #3 : Speciation

Which of the following refers to speciation that results from physical barriers such that biological populations become isolated?

Possible Answers:

Disruptive selection

Allopatric speciation

Sympatric speciation

Natural selection

Parapatric speciation

Correct answer:

Allopatric speciation

Explanation:

The correct answer is allopatric speciation. Sympatric speciation occurs when two biological populations inhabit the same geography, but speciate due to behavorial differences. Parapatric speciation occurs when there is a small hybrid zone or overlap of two biogeographically distinct populations. Disruptive selection and natural selection do not explain events of speciation in the context of the question. 

Example Question #4 : Speciation

Which of the following refers to speciation that occurs due to reproductive isolation in populations that occupy the same geographical area?

Possible Answers:

Parapatric speciation 

None of the other answers

Balancing selection

Allopatric speciation

Sympatric speciation 

Correct answer:

Sympatric speciation 

Explanation:

The correct answer is sympatric speciation. Although rare, sympatric speciation occurs in populations that occupy the same geography, but still develop reproductive isolation. This isolation is generally driven by behavioral differences. Allopatric speciation occurs in biogeographically distinct populations. Parapatric speciation occurs when there is a small hybrid zone or overlap of two biogeographically distinct populations. Balancing selection refers to a mode of natural selection, not speciation. 

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