The Antarctic Circumpolar Current as a diversification trigger for deep-sea octocorals.
The Antarctic Circumpolar Current as a diversification trigger for deep-sea octocorals.
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DOI：
10.1186/s12862-015-0574-z
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发表时间：
2016-01-04
影响因子：
3.4
通讯作者：
Sánchez JA
中科院分区：
文献类型：
--
作者：
Dueñas LF;Tracey DM;Crawford AJ;Wilke T;Alderslade P;Sánchez JA
南极洲被南极绕极流（ACC）包围，这是世界上最大最强的洋流。尽管它对于塑造生物地理格局具有潜在的重要性，但对 ACC 深海种群的分布和连通性仍然知之甚少。在这项研究中，我们对南太平洋和南大洋深海八珊瑚的系统发育地理学模式进行了首次评估，特别是一组密切相关的瓶刷八珊瑚（Primnoidae：Tokoprymno 和 Thourella），作为研究 ACC 对育雏物种种群结构影响的测试案例。我们评估了 ACC 对北部和南部种群之间的基因流动构成障碍的程度，以及这些珊瑚多样化的开始是否与 ACC（渐新世-中新世边界）的起源一致。基于 80 个个体的两个核基因的 DNA 序列以及系统发育地理学模型测试方法的组合，我们发现了与 ACC 空间发生相对应的系统发育断裂。我们还在我们的四个区域人群中发现了显着的遗传结构。然而，我们发现了某些种群对之间共有的单倍型，这表明长距离、不对称的迁徙。我们的分歧时间分析表明，两栖 ACC 种群的分离发生在大约 1260 万年前的中中新世，即 ACC 形成之后。我们认为 ACC 对这些深海八珊瑚构成了半渗透性屏障，能够分离和构建种群，同时允许短期的基因流动。中新世期间 ACC 纬度位置的波动可能导致了这些八珊瑚的多样化。此外，我们提供的证据表明，我们四个采样区域的种群实际上可能构成不同的物种。本文的在线版本 (doi:10.1186/s12862-015-0574-z) 包含补充材料，可供授权用户使用。
Antarctica is surrounded by the Antarctic Circumpolar Current (ACC), the largest and strongest current in the world. Despite its potential importance for shaping biogeographical patterns, the distribution and connectivity of deep-sea populations across the ACC remain poorly understood. In this study we conducted the first assessment of phylogeographical patterns in deep-sea octocorals in the South Pacific and Southern Ocean, specifically a group of closely related bottlebrush octocorals (Primnoidae: Tokoprymno and Thourella), as a test case to study the effect of the ACC on the population structure of brooding species. We assessed the degree to which the ACC constitutes a barrier to gene flow between northern and southern populations and whether the onset of diversification of these corals coincides with the origin of the ACC (Oligocene-Miocene boundary). Based on DNA sequences of two nuclear genes from 80 individuals and a combination of phylogeographic model-testing approaches we found a phylogenetic break corresponding to the spatial occurrence of the ACC. We also found significant genetic structure among our four regional populations. However, we uncovered shared haplotypes among certain population pairs, suggesting long-distance, asymmetrical migration. Our divergence time analyses indicated that the separation of amphi-ACC populations took place during the Middle Miocene around 12.6 million years ago, i.e., after the formation of the ACC. We suggest that the ACC constitutes a semi-permeable barrier to these deep-sea octocorals capable of separating and structuring populations, while allowing short periods of gene flow. The fluctuations in latitudinal positioning of the ACC during the Miocene likely contributed to the diversification of these octocorals. Additionally, we provide evidence that the populations from each of our four sampling regions could actually constitute different species. The online version of this article (doi:10.1186/s12862-015-0574-z) contains supplementary material, which is available to authorized users.