A. Disruptive selection
B. Directional selection
C. Stabilizing selection
D. No selection
参考答案:
B
本题详细解析:
In directional selection, the population favours one extreme, as they are better adapted to the environment. Giraffes with longer necks have longer lifespans. Choice B is correct.
Choice A is incorrect, as disruptive selection would result in the extremes being favoured, i.e. giraffes with shorter and longer necks would have longer lifespans. Choice C is incorrect as stabilising selection would result in the intermediate neck lengths having the longest lifespans. Choice D is incorrect as long-necked giraffes are being ‘selected’ for.
