Evolutionary Biology Centre, Department of Ecology and Evolution, Animal Ecology, Uppsala University, Norbyvägen 18D, Uppsala, Sweden.
J Evol Biol. 2010 Sep 1;23(9):1857-67. doi: 10.1111/j.1420-9101.2010.02050.x. Epub 2010 Jul 14.
Speciation is thought to often result from indirect selection for reproductive isolation. This will occur when reproductive traits that cause reproductive isolation evolve (i) as a by-product of natural selection on traits with which they are genetically correlated or (ii) as an indirect result of diversifying sexual selection. Here, we use experimental evolution to study the degree of divergent evolution of reproductive traits by manipulating the intensity of natural and sexual selection in replicated selection lines of seed beetles. Following 40 generations of selection, we assayed the degree of divergent evolution of reproductive traits between replicate selection lines experiencing the same selection regime. The evolution of reproductive traits was significantly divergent across selection lines within treatments. The evolution of reproductive traits was both slower and, more importantly, significantly less divergent among lines experiencing stronger directional natural selection. This suggests that reproductive traits did not evolve as an indirect by-product of adaptation. We discuss several ways in which natural selection may hamper divergent evolution among allopatric populations.
物种形成通常被认为是生殖隔离的间接选择的结果。当导致生殖隔离的生殖特征（i）作为与它们在遗传上相关的特征的自然选择的副产品进化，或者（ii）作为多样化的性选择的间接结果进化时，就会发生这种情况。在这里，我们使用实验进化来研究通过在重复选择的种子甲虫中操纵自然选择和性选择的强度来研究生殖特征的分歧进化程度。经过 40 代的选择，我们在经历相同选择制度的重复选择系中检测了生殖特征的分歧进化程度。在处理过程中，生殖特征在选择系之间的进化明显不同。生殖特征的进化在经历更强的定向自然选择的系中既更慢，更重要的是，明显分歧较小。这表明生殖特征不是作为适应的间接副产品进化的。我们讨论了自然选择可能阻碍异域种群之间分歧进化的几种方式。
