Langerhans R Brian, Gifford Matthew E, Joseph Everton O
Department of Biology, Washington University, St. Louis, Missouri 63130, USA.
Evolution. 2007 Sep;61(9):2056-74. doi: 10.1111/j.1558-5646.2007.00171.x.
Although theory indicates that natural selection can facilitate speciation as a by-product, demonstrating ongoing speciation via this by-product mechanism in nature has proven difficult. We examined morphological, molecular, and behavioral data to investigate ecology's role in incipient speciation for a post-Pleistocene radiation of Bahamas mosquitofish (Gambusia hubbsi) inhabiting blue holes. We show that adaptation to divergent predator regimes is driving ecological speciation as a by-product. Divergence in body shape, coupled with assortative mating for body shape, produces reproductive isolation that is twice as strong between populations inhabiting different predator regimes than between populations that evolved in similar ecological environments. Gathering analogous data on reproductive isolation at the interspecific level in the genus, we find that this mechanism of speciation may have been historically prevalent in Gambusia. These results suggest that speciation in nature can result as a by-product of divergence in ecologically important traits, producing interspecific patterns that persist long after speciation events have completed.
尽管理论表明自然选择可以作为一种副产品促进物种形成，但要在自然界中证明通过这种副产品机制正在进行的物种形成却很困难。我们研究了形态学、分子学和行为学数据，以调查生态在巴哈马食蚊鱼（Gambusia hubbsi）后更新世辐射形成过程中对初始物种形成的作用，这些食蚊鱼栖息在蓝洞中。我们发现，对不同捕食者环境的适应正在作为一种副产品推动生态物种形成。体型差异，再加上对体型的选型交配，产生了生殖隔离，在栖息于不同捕食者环境的种群之间，生殖隔离强度是在相似生态环境中进化的种群之间的两倍。收集该属种间水平上关于生殖隔离的类似数据，我们发现这种物种形成机制在食蚊鱼属中可能在历史上很普遍。这些结果表明，自然界中的物种形成可能是生态重要性状分化的副产品，产生的种间模式在物种形成事件完成后仍会长期持续。
