Department of Biology, Queens College, The City University of New York, Queens, NY, USA; The Graduate Center, The City University of New York, New York, NY, USA.
Department of Biology, Queens College, The City University of New York, Queens, NY, USA; The Graduate Center, The City University of New York, New York, NY, USA.
Mol Phylogenet Evol. 2014 Feb;71:157-69. doi: 10.1016/j.ympev.2013.11.015. Epub 2013 Dec 6.
The Ethiopian highlands are a biodiversity hotspot characterized by a high level of endemism, particularly in amphibians. Frogs of the genus Ptychadena have experienced an evolutionary radiation in these highlands. Thus, this group provides an excellent opportunity to study the process of speciation in this important biogeographic area. We sequenced two mitochondrial (16S and COI) and four nuclear (Rag-1, CXCR4, NCX1 and Tyr) genes in a sample of 236 frogs from 49 Ethiopian localities. Phylogenetic analyses of the mitochondrial genes revealed the presence of eight divergent mitochondrial lineages. We uncovered a near perfect concordance between these lineages and genetic clusters based on nuclear sequences. A Bayesian species delimitation analysis confirmed that these eight lineages correspond to eight genetically isolated populations which may represent eight species. Some of these species have already been recognized due to their distinct morphology (P. cooperi, P. nana and P. erlangeri) but we determined that the species P. neumanni is a complex of 5 cryptic species, thus increasing substantially the number of species in this genus and for this country. We resolved the phylogeny of Ethiopian highland Ptychadena using a species tree approach and determined that Ptychadena species group on the phylogeny according to their habitat preference. We propose that the diversity of Ethiopian Ptychadena results from an early phase of specialization to distinct elevations followed by a phase of ecological diversification within each elevational range. We estimated that the early phase of diversification of Ethiopian Ptychadena probably occurred in the late Miocene and the most recent speciation events in the late-Pliocene or Pleistocene.
埃塞俄比亚高原是一个生物多样性热点地区，具有高度的特有性，尤其是在两栖动物中。在这些高地上，Ptychadena 属的青蛙经历了进化辐射。因此，该组为研究这一重要生物地理区域的物种形成过程提供了极好的机会。我们对来自埃塞俄比亚 49 个地点的 236 只青蛙样本进行了两个线粒体（16S 和 COI）和四个核（Rag-1、CXCR4、NCX1 和 Tyr）基因的测序。线粒体基因的系统发育分析显示存在 8 个分化的线粒体谱系。我们发现这些谱系与基于核序列的遗传聚类之间存在近乎完美的一致性。贝叶斯物种delimitation 分析证实，这 8 个谱系对应于 8 个遗传隔离的种群，可能代表 8 个物种。其中一些物种由于其独特的形态（P. cooperi、P. nana 和 P. erlangeri）已经得到了认可，但我们确定 P.neumanni 物种是 5 个隐种的复合体，因此大大增加了该属和该国的物种数量。我们使用物种树方法解决了埃塞俄比亚高原 Ptychadena 的系统发育问题，并确定 Ptychadena 物种在系统发育树上根据其栖息地偏好聚类。我们提出，埃塞俄比亚 Ptychadena 的多样性源于早期向不同海拔高度的专业化阶段，随后在每个海拔范围内经历了生态多样化阶段。我们估计，埃塞俄比亚 Ptychadena 的早期多样化阶段可能发生在中新世晚期，最近的物种形成事件发生在上新世或更新世。
