Ecological Genetics Research Unit, Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
J Evol Biol. 2011 Jan;24(1):206-18. doi: 10.1111/j.1420-9101.2010.02161.x. Epub 2010 Nov 2.
Patterns of genetic variation and covariation can influence the rate and direction of phenotypic evolution. We explored the possibility that the parallel morphological evolution seen in threespine stickleback (Gasterosteus aculeatus) populations colonizing freshwater environments is facilitated by patterns of genetic variation and covariation in the ancestral (marine) population. We estimated the genetic (G) and phenotypic (P) covariance matrices and directions of maximum additive genetic (g(max) ) and phenotypic (p(max) ) covariances of body shape and armour traits. Our results suggest a role for the ancestral G in explaining parallel morphological evolution in freshwater populations. We also found evidence of genetic constraints owing to the lack of variance in the ancestral G. Furthermore, strong genetic covariances and correlations among traits revealed that selective factors responsible for threespine stickleback body shape and armour divergence may be difficult to disentangle. The directions of g(max) and p(max) were correlated, but the correlations were not high enough to imply that phenotypic patterns of trait variation and covariation within populations are very informative of underlying genetic patterns.
遗传变异和协变模式会影响表型进化的速度和方向。我们探讨了一个可能性，即在适应淡水环境的三刺鱼（Gasterosteus aculeatus）种群中观察到的平行形态进化是否受到祖先（海洋）种群中遗传变异和协变模式的影响。我们估计了身体形状和盔甲特征的遗传（G）和表型（P）协方差矩阵，以及最大加性遗传（g(max)）和表型（p(max)）协方差的方向。我们的结果表明，祖先 G 在解释淡水种群中的平行形态进化中起着作用。我们还发现了由于祖先 G 缺乏方差而导致遗传限制的证据。此外，性状之间强烈的遗传协方差和相关性表明，导致三刺鱼身体形状和盔甲分化的选择因素可能难以区分。g(max)和 p(max)的方向相关，但相关程度不足以表明群体内性状变异和协变的表型模式对潜在遗传模式非常有启发性。
