title: Explosive radiation or uninformative genes? Origin and early diversification of tachinid flies (Diptera: Tachinidae).
abstract: Molecular phylogenetic studies at all taxonomic levels often infer rapid radiation events based on short, poorly resolved internodes. While such rapid episodes of diversification are an important and widespread evolutionary phenomenon, much of this poor phylogenetic resolution may be attributed to the continuing widespread use of "traditional" markers (mitochondrial, ribosomal, and some nuclear protein-coding genes) that are often poorly suited to resolve difficult, higher-level phylogenetic problems. Here we reconstruct phylogenetic relationships among a representative set of taxa of the parasitoid fly family Tachinidae and related outgroups of the superfamily Oestroidea. The Tachinidae are one of the most species rich, yet evolutionarily recent families of Diptera, providing an ideal case study for examining the differential performance of loci in resolving phylogenetic relationships and the benefits of adding more loci to phylogenetic analyses. We assess the phylogenetic utility of nine genes including both traditional genes (e.g., CO1 mtDNA, 28S rDNA) and nuclear protein-coding genes newly developed for phylogenetic analysis. Our phylogenetic findings, based on a limited set of taxa, include: a close relationship between Tachinidae and the calliphorid subfamily Polleninae, monophyly of Tachinidae and the subfamilies Exoristinae and Dexiinae, subfamily groupings of Dexiinae+Phasiinae and Tachininae+Exoristinae, and robust phylogenetic placement of the somewhat enigmatic genera Strongygaster, Euthera, and Ceracia. In contrast to poor resolution and phylogenetic incongruence of "traditional genes," we find that a more selective set of highly informative genes is able to more precisely identify regions of the phylogeny that experienced rapid radiation of lineages, while more accurately depicting their phylogenetic context. Although much expanded taxon sampling is necessary to effectively assess the monophyly of and relationships among major tachinid lineages and their relatives, we show that a small number of well-chosen nuclear protein-coding genes can successfully resolve even difficult phylogenetic problems.
authors.affiliation: Department of Biological Sciences, Wright State University, Dayton, OH 45435, USA; Department of Biology, Linfield College, McMinnville, OR 97128, USA.
authors.forename: Isaac S
authors.initials: IS
authors.lastname: Winkler
authors.affiliation: Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Blaschke
authors.affiliation: Department of Biological Sciences, Wright State University, Dayton, OH 45435, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Davis
authors.affiliation: Department of Biological Sciences, Wright State University, Dayton, OH 45435, USA. Electronic address: john.stireman@wright.edu.
authors.forename: John O
authors.initials: JO
authors.lastname: Stireman
authors.affiliation: Canadian National Collection of Insects, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, Ontario K1A 0C6, Canada.
authors.forename: James E
authors.initials: JE
authors.lastname: O'Hara
authors.affiliation: DAFNAE-Entomology, Università degli Studi di Padova, Viale dell'Università 16, 35020 Legnaro (Padova), Italy; Dipartimento di Biologia e Biotecnologie 'Charles Darwin', 'Sapienza' Università di Roma, Piazzale A. Moro 5, 00185 Rome, Italy.
authors.forename: Pierfilippo
authors.initials: P
authors.lastname: Cerretti
authors.affiliation: Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: John K
authors.initials: JK
authors.lastname: Moulton
mesh_terms: D000818:Animals; D004175:Diptera / Q000145:classification* / Q000235:genetics; D017344:Genes, Insect; D019476:Insect Proteins / Q000235:genetics; D024101:Mitochondrial Proteins / Q000235:genetics; D010802:Phylogeny
chemical_list: D019476:Insect Proteins; D024101:Mitochondrial Proteins
keywords: Molecular phylogenetics; Oestroidea; Phylogenetic informativeness; Pollenia; Rapid radiation