Long-distance island hopping without dispersal stages: transportation across major zoogeographic barriers in a Southern Ocean isopod
Long-distance island hopping without dispersal stages: transportation across major zoogeographic barriers in a Southern Ocean isopod
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DOI：
10.1007/s00114-010-0674-y
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发表时间：
2010-05
影响因子：
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通讯作者：
F. Leese;Shobhit Agrawal;C. Held
中科院分区：
文献类型：
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作者：
F. Leese;Shobhit Agrawal;C. Held
物种的完整性，只有保持经常性等位基因交换的亚群之间发生的迁移标本。根据观察到的或假定的海洋物种的流动性来预测这种基因流动已证明是容易出错的。利用一个线粒体基因和7个微卫星标记，我们研究了遗传结构和基因流在Septemserolis septemcarinata，一个严格的底栖物种缺乏浮游幼虫和游泳的能力。三个偏远岛屿（南格鲁吉亚、布韦和马里恩岛）周围适宜的浅水生境在地理上是分离的，被2 000多公里的不适宜居住的深海（东西向）隔开，也被极地锋（南北向）隔开，极地锋是许多海洋生物群的有力分界线。虽然我们确实发现了三个岛屿种群之间的遗传分化，但我们的研究结果也表明，最近的基因流动最好地解释了我们的数据。一个模型假设没有基因流后，最初的殖民化的岛屿执行显着更差。这些测试也有利于不对称的基因流模式（西向东和东向西），从而反映了该地区主要洋流的方向性。我们的结论是，观察到的模式一定是罕见的远距离传播，而不是邻近或人为介导的运输。作为一种机制，我们提出了被动漂流在南极绕极流漂浮基质。结果表明，物理屏障的有效性不仅是其物理参数的函数，而且在很大程度上取决于生物体与环境的相互作用。
Species integrity is maintained only if recurrent allelic exchange between subpopulations occurs by means of migrating specimens. Predictions of this gene flow on the basis of observed or assumed mobility of marine species have proven to be error-prone. Using one mitochondrial gene and seven microsatellite markers, we studied the genetic structure and gene flow inSeptemserolis septemcarinata, a strictly benthic species lacking pelagic larvae and the ability to swim. Suitable shallow-water habitats around three remote islands (South Georgia, Bouvet, and Marion Island) are geographically disjunct, isolated by more than 2,000 km of uninhabitable deep sea (east–west) and also separated by the Polar Front (north–south), which serves as a strong demarcation line in many marine taxa. Although we did find genetic differentiation among the three island populations, our results also revealed that a scenario with recent gene flow explains our data best. A model assuming no gene flow after initial colonization of the islands performs significantly worse. The tests also favor an asymmetric gene flow pattern (west to east ≫ east to west) thus mirroring the directionality of major oceanographic currents in the area. We conclude that rare long-distance dispersal rather than vicariance or human-mediated transport must be responsible for the observed patterns. As a mechanism, we propose passive rafting on floating substrata in the Antarctic Circumpolar Current. The results demonstrate that the effectiveness of a physical barrier is not solely a function of its physical parameters but strongly depends on how organisms interact with their environment.