Broad polyphyly and historical biogeography of the neotropical wasp genus Notiospathius (Braconidae: Doryctinae)

摘要

Morphological convergence is a frequently observed pattern that occurs in species with similar environments, trophic niches, and/or life history strategies. In particular, adaptive morphological convergence is common in small, highly diverse invertebrate taxa sharing similar life history strategies such as parasitoidism. The genus Notiospathius is a braconid parasitoid wasp group with a vast, undetermined number of species distributed throughout the Neotropics. Members of this genus possess a considerably elongated, petiolate first metasomal tergite. This structure, however, also occurs in species of other doryctine genera, both closely and distantly related, probably due to adaptation for attacking wood and bark boring coleopteran larvae. Here we investigated the phylogenetic relationships among 117 species assigned to Notiospathius, including species of its closely related genera Masonius and Tarasco, as well as members of a number of other doryctine genera in order to test its monophyly. Separate and concatenated Bayesian partitioned analyses were carried out using two mitochondrial and three nuclear gene markers. The influence of each gene on the overall topology was verified using a cross-validation analysis for each marker with a "leave-one-out" approach. Moreover, the historical biogeography of Notiospathius was assessed calculating divergence time estimates of clades with BEAST and performing ancestral area reconstruction analyses both with RASP (Bayesian and S-DIVA) and Lagrange (DEC). All analyses recovered a polyphyletic Notiospathius consisting of three separate clades that were more related to other doryctine genera than to each other. The relationships reconstructed could not be used to confidently establish the limits of Notiospathius with respect to its closely related genera Tarasco and Masonius, and thus the generic status of the latter two taxa is maintained. Our divergence time estimates and ancestral area reconstructions indicate that the most recent common ancestor of Notiospathius sensu stricto originated in the Caribbean subregion during the Oligocene-Miocene boundary, and subsequently diversified during the mid- to late Miocene, radiating throughout the Neotropics.