Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
Integr Comp Biol. 2011 Oct;51(4):580-97. doi: 10.1093/icb/icr104.
Although a number of recent studies of marine holoplankton have reported significant genetic structure among populations, little is currently known about the biological and oceanographic processes that influence population connectivity in oceanic plankton. In order to examine how depth preferences influence dispersal in oceanic plankton, I characterized the genetic structure of a copepod with diel vertical migration (DVM) (Pleuromamma xiphias), throughout its global distribution, and compared these results to those expected given the interaction of this species' habitat depth with ocean circulation and bathymetry. Mitochondrial COI sequences from 651 individuals from 28 sites in the Indian, Pacific, and Atlantic Oceans revealed highly significant genetic differentiation both within and among ocean basins. Limited dispersal among distinct pelagic provinces seems to have played a major role in population differentiation in this species, with strong genetic breaks observed across known oceanographic fronts or current systems in all three ocean basins. The Indo-West Pacific (IWP) holds a highly distinct genetic population of this species that was sampled in both the western Pacific and eastern Indian Oceans. This suggests that the IWP does not act as a strong barrier to gene flow between basins, as expected, despite the relatively shallow water depth (<200 m) and vertically extensive (>400 m) diel migration of this species. A pattern of isolation by distance was observed in the Indian Ocean with genetic differentiation among samples down to spatial scales of ∼800 km, indicating that realized dispersal in P. xiphias occurs over much smaller spatial scales than in previously reported oceanic holoplankton. Given its highly regionalized population genetic structure, P. xiphias may have some capacity to adapt to local oceanographic conditions, and it should not be assumed that populations of this species in distinct pelagic biomes will respond in the same way to shared physical or climatic forcing.
尽管最近有一些关于海洋浮游生物的研究报告称，在种群之间存在显著的遗传结构，但目前对于影响海洋浮游生物种群连通性的生物和海洋过程知之甚少。为了研究深度偏好如何影响海洋浮游生物的扩散，我对具有昼夜垂直迁移（DVM）的桡足类（Pleuromamma xiphias）进行了遗传结构特征描述，研究范围涵盖其全球分布，并将这些结果与该物种栖息地深度与海洋环流和海底地形相互作用所预期的结果进行了比较。从来自印度洋、太平洋和大西洋 28 个地点的 651 个个体的线粒体 COI 序列中发现，无论是在海洋盆地内部还是在海洋盆地之间，都存在着高度显著的遗传分化。在这个物种中，不同的浮游生物区系之间有限的扩散似乎在种群分化中发挥了主要作用，在所有三个大洋中，在已知的海洋学锋面或当前系统中都观察到了强烈的遗传断裂。西太平洋-印度洋区（IWP）拥有一个高度独特的该物种遗传种群，该种群在西太平洋和东印度洋都有采样。这表明，尽管该物种的水层相对较浅（<200 米）且昼夜垂直迁移范围较广（>400 米），但 IWP 并没有像预期的那样成为阻止两大洋之间基因流动的强大障碍。在印度洋中观察到了一种隔离距离的模式，在样本之间存在遗传分化，直到 800 公里左右的空间尺度，这表明 P. xiphias 的实际扩散发生在比以前报道的海洋浮游生物更小的空间尺度上。考虑到其高度区域化的种群遗传结构，P. xiphias 可能具有一定的适应本地海洋条件的能力，不应该假设在不同的远洋生物群系中，该物种的种群会以相同的方式对共同的物理或气候胁迫做出反应。
