Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki, Finland.
Evolution. 2011 Jun;65(6):1800-7. doi: 10.1111/j.1558-5646.2011.01247.x. Epub 2011 Mar 10.
Examples of parallel evolution of phenotypic traits have been repeatedly demonstrated in threespine sticklebacks (Gasterosteus aculeatus) across their global distribution. Using these as a model, we performed a targeted genome scan--focusing on physiologically important genes potentially related to freshwater adaptation--to identify genetic signatures of parallel physiological evolution on a global scale. To this end, 50 microsatellite loci, including 26 loci within or close to (<6 kb) physiologically important genes, were screened in paired marine and freshwater populations from six locations across the Northern Hemisphere. Signatures of directional selection were detected in 24 loci, including 17 physiologically important genes, in at least one location. Although no loci showed consistent signatures of selection in all divergent population pairs, several outliers were common in multiple locations. In particular, seven physiologically important genes, as well as reference ectodysplasin gene (EDA), showed signatures of selection in three or more locations. Hence, although these results give some evidence for consistent parallel molecular evolution in response to freshwater colonization, they suggest that different evolutionary pathways may underlie physiological adaptation to freshwater habitats within the global distribution of the threespine stickleback.
在全球分布范围内，三刺鱼（Gasterosteus aculeatus）中已经多次证明了表型特征的平行进化。我们以这些鱼为模型，进行了靶向基因组扫描——专注于可能与淡水适应相关的生理重要基因——以确定全球范围内平行生理进化的遗传特征。为此，我们在北半球六个地点的成对海洋和淡水种群中筛选了 50 个微卫星基因座，包括 26 个位于或靠近（<6 kb）生理重要基因的基因座。在至少一个地点，在 24 个基因座中检测到了定向选择的特征，其中包括 17 个生理重要基因。尽管没有基因座在所有具有差异的种群对中都表现出一致的选择特征，但在多个地点有几个异常值是共同的。特别是，七个生理重要基因以及参考外胚层发育蛋白基因（EDA）在三个或更多地点显示出选择的特征。因此，尽管这些结果为应对淡水殖民化而进行的一致平行分子进化提供了一些证据，但它们表明，在三刺鱼的全球分布范围内，对淡水栖息地的生理适应可能有不同的进化途径。
