Evanno G, Castella E, Goudet J
Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
J Evol Biol. 2006 Jul;19(4):1071-82. doi: 10.1111/j.1420-9101.2006.01098.x.
Detecting the action of selection in natural populations can be achieved using the QST-FST comparison that relies on the estimation of FST with neutral markers, and QST using quantitative traits potentially under selection. QST higher than FST suggests the action of directional selection and thus potential local adaptation. In this article, we apply the QST-FST comparison to four populations of the hermaphroditic freshwater snail Radix balthica located in a floodplain habitat. In contrast to most studies published so far, we did not detect evidence of directional selection for local optima for any of the traits we measured: QST calculated using three different methods was never higher than FST. A strong inbreeding depression was also detected, indicating that outcrossing is probably predominant over selfing in the studied populations. Our results suggest that in this floodplain habitat, local adaptation of R. balthica populations may be hindered by genetic drift, and possibly altered by uneven gene flow linked to flood frequency.
利用QST-FST比较法可以检测自然种群中的选择作用，该方法依赖于用中性标记估计FST，并利用可能处于选择作用下的数量性状估计QST。QST高于FST表明存在定向选择作用，从而可能存在局部适应性。在本文中，我们将QST-FST比较法应用于位于洪泛区栖息地的雌雄同体淡水螺——圆扁螺的四个种群。与迄今为止发表的大多数研究不同，我们没有检测到我们所测量的任何性状存在针对局部最优值的定向选择证据：使用三种不同方法计算的QST从未高于FST。我们还检测到强烈的近亲繁殖衰退，这表明在所研究的种群中，异交可能比自交更为普遍。我们的结果表明，在这个洪泛区栖息地，圆扁螺种群的局部适应性可能受到遗传漂变的阻碍，并可能因与洪水频率相关的不均匀基因流而改变。
