Murphy Nicholas, Banks Jonathan C, Whitfield James B, Austin Andrew D
Australian Centre for Evolutionary Biology and Biodiversity, School of Earth and Environmental Science, The University of Adelaide, SA 5005, Australia.
Mol Phylogenet Evol. 2008 Apr;47(1):378-95. doi: 10.1016/j.ympev.2008.01.022. Epub 2008 Jan 31.
The microgastroid complex of braconid wasps is a widely recognized and biologically coherent lineage of endoparasitoids of lepidopteran larvae (caterpillars). The complex has received significant phylogenetic attention in recent years due in part to the taxons' association with mutualistic polydnaviruses, with which they compromise host immune systems. A number of previous attempts using a variety of morphological and molecular approaches have not unequivocally resolved relationships amongst the main subfamilies. This work represents a more extensive attempt to resolve the microgastroid relationships, using seven genes (16S rRNA, cytochrome oxidase I (CO1), 28S rRNA, arginine kinase (ArgK), long wavelength rhodopsin (Ops), elongation factor 1 alpha (EF1a) and wingless (Wg)) and a greater taxonomic representation. Bayesian, likelihood and parsimony phylogenetic reconstructions of this improved data set has determined that the chelonines diverged first from the remainder of the microgastroids, however the relationships amongst the other subfamilies are still unclear, suggesting a greater nucleotide sample is required to resolve them. Examination of the contribution of individual gene trees to the phylogeny demonstrates why the relationships between subfamilies are still unclear, with not all groups monophyletic for all trees. Filtered supernetworks demonstrate that monophyly of all subfamilies is only recovered when splits found in only one or two genes are excluded, but this also results in little remaining structure left in the deep nodes to resolve inter-subfamily relationships. By increasing the breadth of the study we were also able to re-evaluate previous attempts at dating the lineage and, therefore the origin of the polydnavirus association. Previous attempts used a much reduced data set and fewer fossil calibrations. Thorough literature searches have revealed a substantial increase in the fossil calibrations and these, combined with more sophisticated molecular dating analysis, have substantially increased the age of the microgastroid lineage from previous estimates of approximately 73MYA to approximately 100MYA. Examination of the resultant linearized clock tree also allows an insight into the evolution of the more species rich subfamilies. The chelonines appear to have had a steady rate of evolution, whilst the microgastrines and cardiochilines appear to have undergone a more significant "burst" of evolution. It is hypothesized that the different parasitism strategies of subfamilies (Chelonines are egg parasitoids and the remainder are larval parasitioids) may have influenced the evolutionary rates of the groups.
茧蜂科的微胃蜂复合体是一种广为人知且在生物学上具有连贯性的鳞翅目幼虫（毛虫）内寄生蜂谱系。近年来，该复合体受到了显著的系统发育学关注，部分原因在于这些分类单元与互利共生的多DNA病毒有关联，它们利用这些病毒来破坏宿主的免疫系统。此前有许多尝试使用各种形态学和分子方法，但都未能明确解决主要亚科之间的关系。这项工作代表了一次更广泛的尝试，旨在解决微胃蜂的关系，使用了七个基因（16S rRNA、细胞色素氧化酶I（CO1）、28S rRNA、精氨酸激酶（ArgK）、长波长视紫红质（Ops）、延伸因子1α（EF1a）和无翅基因（Wg））以及更具代表性的分类群。对这个改进后的数据集进行贝叶斯、似然性和简约性系统发育重建已确定，螯蜂亚科首先从其余微胃蜂中分化出来，然而其他亚科之间的关系仍不明确，这表明需要更多的核苷酸样本才能解决它们之间的关系。对各个基因树对系统发育的贡献进行检查，揭示了亚科之间关系仍不明确的原因，并非所有组在所有树中都是单系的。过滤后的超级网络表明，只有排除仅在一两个基因中发现的分支时，所有亚科的单系性才能恢复，但这也导致在深层节点中几乎没有剩余的结构来解决亚科间的关系。通过扩大研究范围，我们还能够重新评估此前对该谱系以及多DNA病毒关联起源的年代测定尝试。此前的尝试使用的数据集要小得多，且化石校准较少。全面的文献检索发现化石校准有了大幅增加，这些校准与更复杂的分子年代测定分析相结合，已将微胃蜂谱系的年代从先前估计的约7300万年前大幅提高到约1亿年前。对由此产生的线性化时钟树的检查还能让人深入了解物种更丰富的亚科的进化情况。螯蜂亚科似乎具有稳定的进化速率，而微胃蜂亚科和心唇蜂亚科似乎经历了更显著的进化“爆发”。据推测亚科不同的寄生策略（螯蜂亚科是卵寄生蜂，其余是幼虫寄生蜂）可能影响了这些类群的进化速率。
