TPO-31閱讀 #6 - 英檢

Geographic isolation also can proceedslowly, over great spans of time. We find
evidence of such extended events in the fossil record, which affords glimpses
into the breakup of formerly continuousenvironments. For example, during past
ice ages, glaciers advanced down through North America and Europe and gradually
cut off parts of populations from one another. When the glaciers retreated, the
separated populations of plants and animals came into contact again. Some
groups that had descended from the same parent population were no longer
reproductively compatible— they had evolved into separate species. In other
groups, however, genetic divergences had not proceeded so far, and the
descendants could still interbreed— for them, reproductive isolation was not
completed, and so speciation had not.

題目:
Q6 According to paragraph 3, separation of subpopulations by glaciers resulted in
speciation in those groups of plants and animals that

A. were reproductively isolated even after the glaciers disappeared
B. had adjusted to the old conditions caused by the glaciers
C. were able to survive being separated from their parent population
D. had experienced some genetic divergences from their parent population

解答給A
想請問一下為什麼不能選D

我的理解是冰河撤退後造成兩種group
一種:genetic divergence所以分離後的物種無法和另一物種reproductvely compatible
另一種:因reproductive isolation不完全所以一樣可interbreed

A和D兩選項文章都有題及
但為什麼答案是A

有請板上高手們幫忙解答
謝謝!


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