Incongruence between morphological data sets: an example from the evolution of endoparasitism among parasitic wasps (Hymenoptera: Braconidae)

Phylogenetic analyses of molecular and morphological data sets for a group of parasitic wasps (Hymenoptera: Braconidae) give strikingly different results. The molecular data indicate that the major life history transition from ectoparasitism to endoparasitism has occurred independently several times within the family while the morphological data indicate a single origin. Similar incongruent topologies are obtained if the morphological data are partitioned by either of two methods: distinguishing (1) characters of the larval stage and female reproductive system, or (2) characters selected individually by the authors prior to the analysis as likely to be mechanistically associated with endo/ectoparasitism. This result is supported by significant differences in tests of incongruence, and we propose that it is caused by convergence among morphological characters resulting from a shared life history strategy.

针对一类寄生蜂（膜翅目：茧蜂科（Hymenoptera: Braconidae））的分子与形态学数据集开展的系统发育分析（phylogenetic analyses）得出了截然不同的结果。分子数据显示，该科内从外寄生（ectoparasitism）到内寄生（endoparasitism）这一重要生活史转变曾独立发生数次；而形态学数据则表明该转变仅存在单次起源。若采用两种方法之一对形态学数据进行分区处理——即区分（1）幼虫期与雌性生殖系统的特征，或（2）本文作者在分析前单独筛选出的、推测与内/外寄生（endo/ectoparasitism）存在机制关联的特征——均可得到类似的拓扑结构（topologies）不一致结果。这一结果得到了不一致性检验（tests of incongruence）中显著差异的支持，我们推测其成因是共享同一生活史策略的类群间，形态特征发生了趋同演化（convergence）。