Two closely related populations of mice have been separated for many generations by a river. Climatic change causes the river to dry up, thereby bringing the mice populations back into contact in a zone of overlap. Which of the following is not a possible outcome when they meet?
A) They interbreed freely and produce fertile hybrid offspring.
B) They no longer attempt to interbreed.
C) They interbreed in the region of overlap, producing an inferior hybrid. Subsequent interbreeding between inferior hybrids produces progressively superior hybrids over several generations.
D) They remain separate in the extremes of their ranges but develop a persistent hybrid zone in the area of overlap.
E) They interbreed in the region of overlap, but produce sterile offspring.
Four hypotheses on how populations might relate to one another along an environmental gradient.
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Although large, the cougar is more closely related to smaller felines.
The age-dependent curve of salivary progresterone levels in three populations.
Head binding, or artificial deformation, was used by some populations as a sign of identity.
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