Can the current molecular arsenal adequately track rapid divergence events within Simuliidae (Diptera)?
Ancient rapid divergence events, such as those that took place during the Mesozoic, are pervasive in evolution and represent a major challenge to phylogenetic biologists. The number of molecular phylogenetic studies in which rapid divergence has been invoked to account for poor phylogenetic resolution has steadily increased over the past few years. In this study, rapid divergence events are again hypothesized to have taken place, this time within the two major tribes of Simuliidae, Prosimuliini and Simuliini. This inference is based upon the failure of portions of 28S rDNA, EF-1alpha, DDC, PEPCK, and 12S rDNA to adequately reconstruct relationships among their constituent genera and the presence of short internal and long terminal nodes within both tribes for all character partitions of these genes. Sequence divergence, other than synonymous variation within coding genes, was low among genera and node support weak, except largely for those joining morphologically similar taxa previously recognized as closely related. Strong attraction between a long terminal node (Austrosimulium Tonnoir) and a long internal node (Simuliini), is hypothesized to be the reason for strong support for the placement of Austrosimulium as the basal-most lineage in this tribe. In spite of these problems, a preferred tree intended to be a reasonable estimate of simuliid phylogeny is tentatively presented. Based upon the considerable genomic sampling conducted in this and previous studies, it is clear that new types of genes are needed to more adequately resolve rapid divergence phenomena. The CAD and GART loci, currently under development as phylogenetic markers by the author, show greater promise for resolving simuliid relationships than do any of the genes examined herein.
Moulton
John K
JK
Department of Entomology, College of Agriculture and Life Sciences, Forbes Building, The University of Arizona, Tucson, AZ 85721, USA. kevin_moulton@ncssu.edu
D000818:Animals; D001483:Base Sequence; D016000:Cluster Analysis; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D012107:Research Design; D017422:Sequence Analysis, DNA; D012843:Simuliidae / Q000145:classification* / Q000235:genetics*