Phenotypic divergence along lines of genetic variance
Phenotypic divergence along lines of genetic variance
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DOI：
10.1086/426600
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发表时间：
2005-01-01
影响因子：
2.9
通讯作者：
Blows, MW
中科院分区：
文献类型：
--
作者：
McGuigan, K;Chenoweth, SF;Blows, MW
居住在相同环境中的自然种群通常独立地进化出相同的表型。这种复制的进化是否是遗传协变模式所施加的遗传约束的结果？我们寻找形态分歧的方向和遗传方差-协方差矩阵（G）的方向之间的关联，通过使用一个实验系统的形态进化在两个异地nonsister物种的彩虹鱼。重复的人群都Melanotaenia eachamensis和Melanotaenia duboulayi独立适应湖泊与河流的水动力环境。8个研究群体的分歧主轴（z）与最大遗传方差方向（g（max））密切相关，表明进化受到方向性遗传约束。然而，水动力适应的方向是强烈相关的向量G描述相对较小的比例的总遗传方差，只有弱相关的g（最大值）。与此相反，在每个栖息地内的重复种群之间的分歧大致成比例的遗传方差的水平，中性表型分歧的理论预测的结果是一致的。两个种间的分歧也主要是沿着G.因此，我们的研究结果表明，在彩虹鱼的水动力适应不定向约束的优势特征向量的G。没有分区分歧的利益（在这里，水动力适应），由于其他过程的分歧的适应的结果，经验研究可能会高估的G的主要特征向量定向约束适应性进化的潜力。
Natural populations inhabiting the same environment often independently evolve the same phenotype. Is this replicated evolution a result of genetic constraints imposed by patterns of genetic covariation? We looked for associations between directions of morphological divergence and the orientation of the genetic variance-covariance matrix (G) by using an experimental system of morphological evolution in two allopatric nonsister species of rainbow fish. Replicate populations of both Melanotaenia eachamensis and Melanotaenia duboulayi have independently adapted to lake versus stream hydrodynamic environments. The major axis of divergence (z) among all eight study populations was closely associated with the direction of greatest genetic variance (g(max)), suggesting directional genetic constraint on evolution. However, the direction of hydrodynamic adaptation was strongly associated with vectors of G describing relatively small proportions of the total genetic variance, and was only weakly associated with g(max). In contrast, divergence between replicate populations within each habitat was approximately proportional to the level of genetic variance, a result consistent with theoretical predictions for neutral phenotypic divergence. Divergence between the two species was also primarily along major eigenvectors of G. Our results therefore suggest that hydrodynamic adaptation in rainbow fish was not directionally constrained by the dominant eigenvector of G. Without partitioning divergence as a consequence of the adaptation of interest (here, hydrodynamic adaptation) from divergence due to other processes, empirical studies are likely to overestimate the potential for the major eigenvectors of G to directionally constrain adaptive evolution.