Banks Jonathan C, Whitfield James B
Department of Entomology, University of Illinois Urbana-Champaign, 505 S Goodwin Avenue, Urbana, IL 61801, USA.
Mol Phylogenet Evol. 2006 Dec;41(3):690-703. doi: 10.1016/j.ympev.2006.06.001. Epub 2006 Jun 7.
Previous estimates of a generic level phylogeny for the ubiquitous parasitoid wasp subfamily Microgastrinae (Hymenoptera) have been problematic due to short internal branches deep in the phylogeny. These short branches might be attributed to a rapid radiation among the taxa, the use of genes that are unsuitable for the levels of divergence being examined, or insufficient quantity of data. We added over 1200 nucleotides from four nuclear genes to a dataset derived from three genes to produce a dataset of over 3000 nucleotides per taxon. While the number of well-supported short branches in the phylogeny increased, we still did not obtain strong bootstrap support for every node. Parametric and nonparametric bootstrap simulations projected that an enormous, and likely unobtainable, amount of data would be required to get bootstrap support greater than 50% for every node. However, a marked increase in the number of well-supported nodes was seen when we conducted a Bayesian analysis of a combined dataset generated from morphological characters added to the seven gene dataset. Our results suggest that, in some cases, combining morphological and genetic characters may be the most practical way to increase support for short branches deep in a phylogeny.
由于系统发育树深处的内部支系较短，之前对无处不在的寄生蜂小茧蜂亚科（膜翅目）通用水平系统发育的估计一直存在问题。这些短支系可能归因于类群之间的快速辐射、使用了不适用于所研究分歧水平的基因，或者数据量不足。我们将来自四个核基因的1200多个核苷酸添加到一个由三个基因衍生而来的数据集，从而每个分类单元产生了一个超过3000个核苷酸的数据集。虽然系统发育树中得到充分支持的短支系数量增加了，但我们仍然没有为每个节点获得强大的自展支持。参数和非参数自展模拟预测，要使每个节点的自展支持率大于50%，将需要大量且可能无法获得的数据。然而，当我们对由添加到七个基因数据集的形态特征生成的组合数据集进行贝叶斯分析时，得到充分支持的节点数量显著增加。我们的结果表明，在某些情况下，结合形态和遗传特征可能是增加对系统发育树深处短支系支持的最实用方法。
