Associated Scientists at Woods Hole, Woods Hole, MA, USA.
PLoS One. 2012;7(9):e45555. doi: 10.1371/journal.pone.0045555. Epub 2012 Sep 27.
Recent studies have countered the paradigm of seamount isolation, confounding conservation efforts at a critical time. Efforts to study deep-sea corals, one of the dominant taxa on seamounts, to understand seamount connectivity, are hampered by a lack of taxonomic keys. A prerequisite for connectivity is species overlap. Attempts to better understand species overlap using DNA barcoding methods suggest coral species are widely distributed on seamounts and nearby features. However, no baseline has been established for variation in these genetic markers relative to morphological species designations for deep-sea octocoral families. Here we assess levels of genetic variation in potential octocoral mitochondrial barcode markers relative to thoroughly examined morphological species in the genus Narella. The combination of six markers used here, approximately 3350 bp of the mitochondrial genome, resolved 83% of the morphological species. Our results show that two of the markers, ND2 and NCR1, are not sufficient to resolve genera within Primnoidae, let alone species. Re-evaluation of previous studies of seamount octocorals based on these results suggest that those studies were looking at distributions at a level higher than species, possibly even genus or subfamily. Results for Narella show that using more markers provides haplotypes with relatively narrow depth ranges on the seamounts studied. Given the lack of 100% resolution of species with such a large portion of the mitochondrial genome, we argue that previous genetic studies have not resolved the degree of species overlap on seamounts and that we may not have the power to even test the hypothesis of seamount isolation using mitochondrial markers, let alone refute it. Thus a precautionary approach is advocated in seamount conservation and management, and the potential for depth structuring should be considered.
最近的研究反驳了海山隔离的范式，在关键时刻给保护工作带来了困惑。为了研究深海珊瑚（海山生物多样性的主要类群之一），了解海山之间的连通性，人们试图努力编制分类学工具，但缺乏分类学工具的阻碍了这一工作。连通性的一个前提是物种重叠。利用 DNA 条码方法更好地了解物种重叠的尝试表明，珊瑚物种在海山及其附近特征上广泛分布。然而，相对于深海八放珊瑚科的形态物种命名，这些遗传标记的变异性还没有建立基线。在这里，我们评估了潜在的八放珊瑚线粒体条码标记相对于 Narella 属中经过彻底检查的形态物种的遗传变异水平。这里使用的六种标记组合，大约 3350bp 的线粒体基因组，解决了 83%的形态物种。我们的结果表明，两个标记 ND2 和 NCR1 不足以解决 Primnoidae 属内的属，更不用说物种了。基于这些结果对以前的海山八放珊瑚研究进行重新评估表明，这些研究观察的分布水平高于物种，甚至可能是属或亚科。Narella 的结果表明，使用更多的标记可以提供在研究海山的相对较窄深度范围内的单倍型。考虑到如此大比例的线粒体基因组，物种的分辨率只有 100%，我们认为，以前的遗传研究还没有确定海山上物种重叠的程度，我们甚至可能没有能力使用线粒体标记来验证海山隔离的假设，更不用说反驳它了。因此，在海山保护和管理中应提倡谨慎的方法，并应考虑深度结构的可能性。
