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) an increasing number of infertile hybrids is produced over the course of the next 100 generations
C) no reproduction occurs in the hybrid zone
D) an increasing number of viable, fertile hybrids is produced over the course of the next 100 generations
E) a decreasing number of viable, fertile hybrids is produced over the course of the next 100 generations

Question

Quizplus · Accepted Answer

The phenomenon of fusion occurs when two populations meet again after a period of geographic isolation and an increasing number of viable, fertile hybrids is produced over time. This results in the gene pools of the two populations mixing to the extent that they become one population with shared characteristics. Choice A is incorrect because the presence or absence of homologous chromosomes does not necessarily determine the occurrence of fusion. Choice B is incorrect because an increasing number of infertile hybrids would not result in fusion, as they cannot contribute to the gene pool of either population. Choice C is incorrect because if no reproduction occurs in the hybrid zone, there would be no hybrid offspring contributing to the gene pool. Choice E is incorrect because a decreasing number of viable, fertile hybrids would not result in fusion as the populations would eventually separate again.

The Phenomenon of Fusion Is Likely to Occur When, After