Liou Lily W, Price Trevor D
Department of Biology, 0116, University of California, San Diego, La Jolla, California, 92093-0116.
Evolution. 1994 Oct;48(5):1451-1459. doi: 10.1111/j.1558-5646.1994.tb02187.x.
The generation of premating isolation given partial or complete postzygotic isolation between populations is termed reinforcement or, in the case of complete isolation, reproductive character displacement. In this study we use computer simulations and a multilocus genetic model to reevaluate the theory of reinforcement. We consider the evolution of female preferences for a male secondary sexual trait. If the populations differ in mean female preference, there is direct selection on the preference for further divergence, which may be augmented by a correlated response to sexual selection on males. Two factors prevent divergence. First, if postzygotic isolation is not complete, gene flow can prevent divergence and lead to a hybrid swarm. This is the usual outcome whenever the average number of breeding adult offspring produced by a hybrid mating is sufficient to replace the parents. Second, one or the other population may become extinct because of the large number of hybrid matings it is involved in. The likelihood of extinction is lowered if population growth rates are high, if hybrids are inviable rather than infertile, or under some conditions when allopatric populations provide immigrants into the contact zone. Provided hybrid fitness is sufficiently low, there is a wide range of genetic and ecological conditions under which reinforcement rather easily occurs, and also a range under which it may occur because of stochastic effects on both the inheritance parameters and the population sizes.
种群之间存在部分或完全合子后隔离时，产生的交配前隔离被称为强化，或者在完全隔离的情况下被称为生殖性状替换。在本研究中，我们使用计算机模拟和多位点遗传模型来重新评估强化理论。我们考虑雌性对雄性第二性征偏好的进化。如果种群在平均雌性偏好上存在差异，就会对偏好进一步分化产生直接选择，这可能会因对雄性性选择的相关反应而增强。有两个因素会阻止分化。首先，如果合子后隔离不完全，基因流会阻止分化并导致杂交群的形成。只要杂交交配产生的成年可育后代的平均数量足以取代亲本，这就是通常的结果。其次，一个或另一个种群可能会因为参与大量杂交交配而灭绝。如果种群增长率高、杂交后代不可育而非不育，或者在某些异地种群为接触区提供移民的条件下，灭绝的可能性就会降低。假设杂交适合度足够低，在广泛的遗传和生态条件下，强化相当容易发生，并且在由于对遗传参数和种群大小的随机效应也可能发生强化的一系列条件下也是如此。
