Wagner A, Wagner G P, Similion P
Yale University Department of Biology, New Haven, Connecticut 06520-8104.
Genetics. 1994 Oct;138(2):533-45. doi: 10.1093/genetics/138.2.533.
The influence of epistasis on the evolution of reproductive isolation by peak shifts is studied in a two-locus two-allele model of a quantitative genetic character under stabilizing selection. Epistasis is introduced by a simple multiplicative term in the function that maps gene effects onto genotypic values. In the model with only additive effects on the trait, the probability of a peak shift and the amount of reproductive isolation are always inversely related, i.e., the higher the peak shift rate, the lower the amount of reproductive isolation caused by the peak shift. With epistatic characters there is no consistent relationship between these two values. Interestingly, there are cases where both transition rates as well as the amount of reproductive isolation are increased relative to the additive model. This effect has two main causes: a shift in the location of the transition point, and the hybrids between the two alternative optimal genotypes have lower average fitness in the epistatic case. A review of the empirical literature shows that the fitness relations resulting in higher peak shift rates and more reproductive isolation are qualitatively the same as those observed for genes causing hybrid inferiority.
在稳定选择下的数量遗传性状的双位点双等位基因模型中，研究了上位性对通过峰值移动实现生殖隔离进化的影响。上位性是通过将基因效应映射到基因型值的函数中的一个简单乘法项引入的。在仅对性状有加性效应的模型中，峰值移动的概率与生殖隔离的程度始终呈负相关，即峰值移动率越高，由峰值移动引起的生殖隔离程度越低。对于上位性性状，这两个值之间没有一致的关系。有趣的是，存在相对于加性模型，转变率以及生殖隔离程度都增加的情况。这种效应有两个主要原因：转变点位置的移动，以及在 epistatic 情况下，两种替代最优基因型之间的杂种具有较低的平均适应性。对实证文献的综述表明，导致更高峰值移动率和更多生殖隔离的适应性关系在质量上与导致杂种劣势基因所观察到的关系相同。
