Zoological Institute, University of Basel, Basel, Switzerland.
J Evol Biol. 2011 Sep;24(9):1975-83. doi: 10.1111/j.1420-9101.2011.02330.x. Epub 2011 Jun 8.
Ecological selection against hybrids between populations occupying different habitats might be an important component of reproductive isolation during the initial stages of speciation. The strength and directionality of this barrier to gene flow depends on the genetic architecture underlying divergence in ecologically relevant phenotypes. We here present line cross analyses of inheritance for two key foraging-related morphological traits involved in adaptive divergence between stickleback ecotypes residing parapatrically in lake and stream habitats within the Misty Lake watershed (Vancouver Island, Canada). One main finding is the striking genetic dominance of the lake phenotype for body depth. Selection associated with this phenotype against first- and later-generation hybrids should therefore be asymmetric, hindering introgression from the lake to the stream population but not vice versa. Another main finding is that divergence in gill raker number is inherited additively and should therefore contribute symmetrically to reproductive isolation. Our study suggests that traits involved in adaptation might contribute to reproductive isolation qualitatively differently, depending on their mode of inheritance.
在物种形成的初始阶段，对占据不同栖息地的种群之间的杂种的生态选择可能是生殖隔离的一个重要组成部分。这种基因流屏障的强度和方向性取决于与生态相关表型分歧相关的遗传结构。在这里，我们对栖息在加拿大温哥华岛 Misty Lake 流域的湖泊和溪流生境中的刺鱼生态型之间适应性分歧所涉及的两个关键觅食相关形态特征的遗传进行了系谱分析。一个主要发现是身体深度的湖泊表型的惊人的遗传显性。因此，针对这种表型的选择应该是不对称的，阻止从湖泊到溪流种群的基因渗入，但反之则不然。另一个主要发现是，鳃耙数的分歧是按加性遗传的，因此应该对称地有助于生殖隔离。我们的研究表明，与适应有关的特征可能会根据其遗传模式在性质上以不同的方式有助于生殖隔离。
