Parapatric speciation and sympatric speciation both describe how populations diverge into separate species without a geographic barrier to dispersal. What distinguishes these two modes of speciation?

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Quizplus · Accepted Answer

Parapatric speciation occurs when populations are adjacent to each other but have limited gene flow, resulting in the evolution of new species. A hybrid zone may exist between the two diverging populations where hybrids are produced, but these hybrids are often less fit than the parental populations and cannot survive or reproduce as well. In contrast, sympatric speciation occurs when two or more species arise from a single population without any physical barrier to gene flow. This can occur through mechanisms such as disruptive selection, polyploidy, or sexual selection. While a hybrid zone may exist in sympatric speciation, it is not a defining characteristic of this process. Therefore, choice B, C, and D are incorrect.

Parapatric Speciation and Sympatric Speciation Both Describe How Populations Diverge