Department of Biology, University of Richmond, Richmond, VA 23173, USA.
BMC Evol Biol. 2012 Dec 10;12:241. doi: 10.1186/1471-2148-12-241.
Over the last ten years we have seen great efforts focused on revising amphibian systematics. Phylogenetic reconstructions derived from DNA sequence data have played a central role in these revisionary studies but have typically under-sampled the diverse frog family Microhylidae. Here, we present a detailed phylogenetic study focused on expanding previous hypotheses of relationships within this cosmopolitan family. Specifically, we placed an emphasis on assessing relationships among New World genera and those taxa with uncertain phylogenetic affinities (i.e., incertae sedis).
One mitochondrial and three nuclear genes (about 2.8 kb) were sequenced to assess phylogenetic relationships. We utilized an unprecedented sampling of 200 microhylid taxa representing 91% of currently recognized subfamilies and 95% of New World genera. Our analyses do not fully resolve relationships among subfamilies supporting previous studies that have suggested a rapid early diversification of this clade. We observed a close relationship between Synapturanus and Otophryne of the subfamily Otophryninae. Within the subfamily Gastrophryninae relationships between genera were well resolved.
Otophryninae is distantly related to all other New World microhylids that were recovered as a monophyletic group, Gastrophryninae. Within Gastrophryninae, five genera were recovered as non-monophyletic; we propose taxonomic re-arrangements to render all genera monophyletic. This hypothesis of relationships and updated classification for New World microhylids may serve as a guide to better understand the evolutionary history of this group that is apparently subject to convergent morphological evolution and chromosome reduction. Based on a divergence analysis calibrated with hypotheses from previous studies and fossil data, it appears that microhylid genera inhabiting the New World originated during a period of gradual cooling from the late Oligocene to mid Miocene.
在过去的十年中，我们看到人们致力于修订两栖动物系统发育。基于 DNA 序列数据的系统发育重建在这些修订研究中发挥了核心作用，但通常对多样化的蛙科 Microhylidae 采样不足。在这里，我们提出了一项详细的系统发育研究，重点是扩展该世界性家族内的关系的先前假说。具体来说，我们强调评估新世界属之间的关系以及那些具有不确定系统发育亲缘关系的分类单元（即，不确定位置）。
我们测序了一个线粒体和三个核基因（约 2.8kb），以评估系统发育关系。我们利用了 200 种 Microhylidae 分类单元的空前采样，代表了目前已识别的亚科的 91%和新世界属的 95%。我们的分析并未完全解决亚科之间的关系，支持了先前表明该分支快速早期多样化的研究。我们观察到 Synapturanus 和 Otophryninae 的 Otophryne 之间存在密切关系。在 Gastrophryninae 亚科中，属之间的关系得到了很好的解决。
Otophryninae 与其他所有作为单系群回收的新世界 Microhylids 都有远缘关系，即 Gastrophryninae。在 Gastrophryninae 中，有五个属被回收为非单系；我们提出了分类调整，以使所有属都成为单系。这种关系假说和新世界 Microhylids 的更新分类可能有助于更好地理解这个明显受到趋同形态进化和染色体减少影响的群体的进化历史。根据与先前研究和化石数据的假说校准的分歧分析，似乎栖息在新世界的 Microhylid 属起源于渐凉时期，从渐新世晚期到中新世中期。
