Department of Biology, Laurentian University 935 Ramsey Lake Road, Sudbury, Ontario, P3E 2C6, Canada.
Ecol Evol. 2013 Jun;3(6):1495-506. doi: 10.1002/ece3.561. Epub 2013 Apr 17.
Population level response to hypoxia has become an issue of global significance because of increased frequency and intensity of hypoxic events worldwide, and the potential for global warming to exacerbate hypoxic stress. In this study, we sequenced two nuclear intronic regions and a single mitochondrial region across seven populations of the African cyprinid, Barbus neumayeri from two river drainages in Uganda: the Rwembaita Swamp-Njuguta River System and the Dura River. We then examined two indices of population structure, G ST and Jost's D, to detect links between oxygen availability and genetic variation and to determine if population genetic structure was associated with (i) dissolved oxygen regime (hypoxia or normoxia), (ii) geographical distance, or (iii) a combination of dissolved oxygen regime and geographical distance. Our results indicate that over a large scale (between drainages), geographical distance significantly affects the genetic structure of populations. However, within a single drainage, dissolved oxygen regime plays a key role in determining the genetic structure of populations. Within the Rwembaita-Njuguta system, gene flow was high between locations of similar oxygen regimes, but low between areas characterized by divergent oxygen regimes. Interestingly, G ST analyses appear to yield less realistic measures of population structure than Jost's D, suggesting that caution must be taken when interpreting and comparing the results from different studies. These results support the idea that aquatic dissolved oxygen can act as a selective force limiting gene flow among populations of aquatic species and therefore should be considered when implementing conservation plans and assessing environmental impact of human activities.
由于全球范围内缺氧事件的频率和强度增加，以及全球变暖可能加剧缺氧胁迫，人口对缺氧的反应已成为一个具有全球意义的问题。在这项研究中，我们对来自乌干达两个河流流域的非洲鲤科鱼类巴氏非洲野鲮 Barbus neumayeri 的七个种群进行了两个核内含子区域和一个单一线粒体区域的测序：Rwembaita 沼泽-Njuguta 河流系统和 Dura 河流。然后，我们检查了两个种群结构指数，G ST 和 Jost 的 D，以检测氧气供应与遗传变异之间的联系，并确定种群遗传结构是否与（i）溶解氧状况（缺氧或正常氧）、（ii）地理距离或（iii）溶解氧状况和地理距离的组合有关。我们的结果表明，在较大的尺度（在流域之间）上，地理距离显著影响种群的遗传结构。然而，在单一流域内，溶解氧状况在决定种群的遗传结构方面起着关键作用。在 Rwembaita-Njuguta 系统内，相似氧气条件下的地点之间基因流动较高，但氧气条件不同的区域之间基因流动较低。有趣的是，G ST 分析似乎比 Jost 的 D 得出的种群结构的现实测量值更不准确，这表明在解释和比较不同研究的结果时必须谨慎。这些结果支持了这样一种观点，即水生溶解氧可以作为一种选择压力，限制水生物种种群之间的基因流动，因此在实施保护计划和评估人类活动对环境的影响时应予以考虑。
