Evidence for asymmetric migration load in a pair of ecologically divergent stickleback populations
Evidence for asymmetric migration load in a pair of ecologically divergent stickleback populations
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DOI：
10.1111/j.1095-8312.2008.00978.x
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发表时间：
2008-06-01
影响因子：
1.9
通讯作者：
Matthews, Blake
中科院分区：
文献类型：
--
作者：
Bolnick, Daniel I.;Caldera, Eric J.;Matthews, Blake
生态不同种群之间的基因流动会阻碍局部适应，导致种群内的平均适应度和方向选择降低。在接收移民比例相对较大的人口中，这种适应不良应该更为严重。我们通过比较不列颠哥伦比亚省相邻但大小不等的湖泊流域的一对三棘棘鱼种群的选择强度来验证这一期望。一个较大的较深的盆地与一个较小的较浅的盆地通过一条短通道相连，这条通道允许种群之间的广泛迁移。两个盆地具有不同的栖息地和猎物群落，棘鱼胃内容物和同位素比值也相应不同。营养形态与饮食相关，因此我们预计这些生态差异会伴随着形态差异。然而，高基因流似乎限制了适应性差异：微卫星显示两个盆地代表一个泛生基因库，表型差异非常微妙。因此，在较小的湖盆中，鱼类受到持续的定向选择，趋向于更底栖的表型，而较大的种群则没有明显的选择。研究结果说明了迁移-选择平衡的潜在不对称效应及其对种群内适合度的影响。(C) 2008 .中国生物医学工程学报，2008,29(4):379 - 379。
Gene flow between ecologically divergent populations can prevent local adaptation, resulting in lower mean fitness and directional selection within a population. Such maladaptation should tend to be stronger in populations receiving a relatively larger fraction of immigrants. We test this expectation by comparing the strength of selection in a pair of three-spine stickleback populations in adjoining but unequal-sized lake basins in British Columbia. A larger deeper basin is connected to a smaller shallower basin by a short channel that allows extensive migration between populations. The two basins contain distinct habitats and prey communities, and stickleback stomach contents and isotope ratios differ accordingly. Trophic morphology is correlated with diet, so we would expect these ecological differences to be accompanied by morphological divergence. However, high gene flow appears to constrain adaptive divergence: microsatellites indicate that the two basins represent a single panmictic gene pool, and phenotypic divergence is very subtle. As a result, fish in the smaller lake basin are subject to persistent directional selection towards a more benthic phenotype, whereas the larger population exhibits no significant selection. The results illustrate the potentially asymmetrical effect of migration-selection balance, and its effect on fitness within populations. (C) 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 273-287.