Museo Nacional de Ciencias Naturales, 28006 Madrid, Spain.
BMC Evol Biol. 2010 Jan 28;10:29. doi: 10.1186/1471-2148-10-29.
Cave organisms have been used as models for evolution and biogeography, as their reduced above-ground dispersal produces phylogenetic patterns of area distribution that largely match the geological history of mountain ranges and cave habitats. Most current hypotheses assume that subterranean lineages arose recently from surface dwelling, dispersive close relatives, but for terrestrial organisms there is scant phylogenetic evidence to support this view. We study here with molecular methods the evolutionary history of a highly diverse assemblage of subterranean beetles in the tribe Leptodirini (Coleoptera, Leiodidae, Cholevinae) in the mountain systems of the Western Mediterranean.
Ca. 3.5 KB of sequence information from five mitochondrial and two nuclear gene fragments was obtained for 57 species of Leptodirini and eight outgroups. Phylogenetic analysis was robust to changes in alignment and reconstruction method and revealed strongly supported clades, each of them restricted to a major mountain system in the Iberian peninsula. A molecular clock calibration of the tree using the separation of the Sardinian microplate (at 33 MY) established a rate of 2.0% divergence per MY for five mitochondrial genes (4% for cox1 alone) and dated the nodes separating the main subterranean lineages before the Early Oligocene. The colonisation of the Pyrenean chain, by a lineage not closely related to those found elsewhere in the Iberian peninsula, began soon after the subterranean habitat became available in the Early Oligocene, and progressed from the periphery to the centre.
Our results suggest that by the Early-Mid Oligocene the main lineages of Western Mediterranean Leptodirini had developed all modifications to the subterranean life and were already present in the main geographical areas in which they are found today. The origin of the currently recognised genera can be dated to the Late Oligocene-Miocene, and their diversification can thus be traced to Miocene ancestors fully adapted to subterranean life, with no evidence of extinct epigean, less modified lineages. The close correspondence of organismal evolution and geological record confirms them as an important study system for historical biogeography and molecular evolution.
洞穴生物一直被用作进化和生物地理学的模型，因为它们在地面上的扩散减少，产生的区域分布的系统发育模式在很大程度上与山脉和洞穴栖息地的地质历史相匹配。大多数当前的假设假设地下谱系是最近从地表扩散的近亲中产生的，但对于陆地生物，几乎没有系统发育证据支持这种观点。我们在这里使用分子方法研究了来自西方地中海山脉系统中的 Leptodirini （鞘翅目，Leiodidae，Cholevinae）族的高度多样化的地下甲虫的进化历史。
我们获得了 57 种 Leptodirini 物种和 8 个外群的五个线粒体和两个核基因片段的约 3.5KB 的序列信息。系统发育分析对对齐和重建方法的变化具有稳健性，揭示了强烈支持的分支，每个分支都局限于伊比利亚半岛的一个主要山脉系统。使用 Sardinian 微板块（在 33 MY）的分离对树进行分子钟校准，为五个线粒体基因建立了 2.0％的分化率/ MY（cox1 单独为 4％），并将分离主要地下谱系的节点追溯到始新世早期之前。由与伊比利亚半岛其他地方发现的无关谱系殖民的比利牛斯山脉链，在始新世早期地下栖息地可用后不久就开始了，并且从外围向中心发展。
我们的结果表明，到早-中始新世，西方地中海 Leptodirini 的主要谱系已经发展出了地下生活的所有特征，并且已经存在于它们今天所在的主要地理区域中。目前公认的属的起源可以追溯到晚始新世-中新世，它们的多样化可以追溯到完全适应地下生活的中新世祖先，没有灭绝的地上、修改较少的谱系的证据。生物进化与地质记录的紧密对应证实了它们作为历史生物地理学和分子进化的重要研究系统。
