Department of Biology and Marine Biology, Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC 28403, USA.
Integr Comp Biol. 2011 Sep;51(3):474-84. doi: 10.1093/icb/icr073. Epub 2011 Jul 8.
Hybridizing populations of blue mussels, Mytilus edulis and Mytilus trossulus, in Cobscook Bay (eastern Maine) have been used by our laboratory to study the evolution of gamete incompatibility and molecular evolution of the vitelline coat lysin proteins expressed in sperm. The M7 lysin locus has been the most studied of the three lysins, but evidence for positive selection necessary to help confirm its role in gamete recognition in western Atlantic hybrid zones is contradictory. We developed an alternative test, based on rates of introgression at M7 lysin. Contrary to expectations, introgression at this locus is much higher (instead of much lower) than is introgression at neutral markers. In this article, we present simulations, constructed using synthetic populations of combinations of admixed genotypes, representing various hybrid offspring categories. Simulations produced variation in introgression across loci, but did not generate the massive introgression at M7 lysin observed in natural populations in Cobscook Bay. We consider these results in the context of selection operating on gamete recognition loci, both within and between species, during the third stage of allopatric speciation in Mytilus.
在缅因州东部的科布斯科特湾，我们实验室利用杂交贻贝种群（蓝贻贝 Mytilus edulis 和厚壳贻贝 Mytilus trossulus）来研究配子不相容性的进化以及在精子中表达的卵黄壳溶菌蛋白的分子进化。M7 溶菌酶基因座是三个溶菌酶中研究最多的，但支持其在西大西洋杂交区配子识别中作用的正选择证据是相互矛盾的。我们开发了一种替代测试方法，基于 M7 溶菌酶的基因渗入率。出乎意料的是，该基因座的基因渗入率（而不是低得多）远高于中性标记的基因渗入率。在本文中，我们提出了模拟，使用混合基因型的合成群体构建，代表各种杂种后代类别。模拟在各个基因座产生了基因渗入的变化，但没有产生在科布斯科特湾自然种群中观察到的 M7 溶菌酶的大量基因渗入。我们在物种内和物种间配子识别基因座的选择作用的背景下考虑这些结果，这是厚壳贻贝第三阶段异域物种形成的第三个阶段。
