Data from: Quantitative genetic inheritance of morphological divergence in a lake-stream stickleback ecotype pair: implications for reproductive isolation

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 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，针对栖息于不同生境的种群间杂交个体的生态选择，可能是生殖隔离的重要组成部分。这种基因流屏障的强度与方向性，取决于与生态相关的表型分化背后的遗传结构。本研究针对加拿大温哥华岛米斯蒂湖流域内邻域分布于湖泊与溪流生境的棘鱼生态型之间的适应性分化相关的两项关键觅食相关形态性状，开展了遗传模式的杂交谱系分析。一项核心发现为：体深性状显著表现为湖泊种群表型的显性遗传。因此，针对该性状的选择对初代及后续世代杂交个体的作用将呈现不对称性，阻碍基因从湖泊种群向溪流种群的渐渗，反之则不受影响。另一项核心发现为：鳃耙数量的分化呈现加性遗传模式，因此将对称地促进生殖隔离的形成。本研究表明，参与适应性演化的性状，依据其遗传模式的不同，可能以不同的作用方式参与生殖隔离的构建。