Universidade de Lisboa, Faculdade de Ciências, Centro de Biologia Ambiental, Campo Grande, Lisbon, Portugal.
Mol Phylogenet Evol. 2012 Jul;64(1):243-53. doi: 10.1016/j.ympev.2012.04.004. Epub 2012 Apr 11.
Lineages undergoing rapid radiations provide exceptional opportunities for studying speciation and adaptation, but also represent a challenge for molecular systematics because retention of ancestral polymorphisms and the occurrence of hybridization can obscure relationships among lineages. Dolphins in the subfamily Delphininae are one such case. Non-monophyly, rapid speciation events, and discordance between morphological and molecular characters have made the inference of phylogenetic relationships within this subfamily very difficult. Here we approach this problem by applying multiple methods intended to estimate species trees using a multi-gene dataset for the Delphininae (Sousa, Sotalia, Stenella, Tursiops, Delphinus and Lagenodelphis). Incongruent gene trees obtained indicate that incomplete lineage sorting and possibly hybridization are confounding the inference of species history in this group. Nonetheless, using coalescent-based methods, we have been able to extract an underlying species-tree signal from divergent histories of independent genes. This is the first time a molecular study provides support for such relationships. This study further illustrates how methods of species-tree inference can be very sensitive both to the characteristics of the dataset and the evolutionary processes affecting the evolution of the group under study.
正在经历快速辐射的谱系为研究物种形成和适应提供了极好的机会，但也对分子系统学构成了挑战，因为祖先多态性的保留和杂交的发生会掩盖谱系之间的关系。海豚亚科就是这样一个例子。非单系性、快速的物种形成事件以及形态和分子特征之间的不匹配，使得推断该亚科内的系统发育关系非常困难。在这里，我们通过应用多种方法来解决这个问题，这些方法旨在使用海豚亚科（宽吻海豚、大西洋领航鲸、瓶鼻海豚、白海豚、真海豚和长喙海豚）的多基因数据集来估计种系发生树。不一致的基因树表明，不完全谱系分选和可能的杂交混淆了对该组物种历史的推断。尽管如此，我们还是能够使用基于合并的方法，从独立基因的分歧历史中提取出潜在的种系发生树信号。这是首次有分子研究为这些关系提供支持。这项研究进一步说明了种系发生树推断方法对数据集的特征和影响研究群体进化的进化过程是多么敏感。
