Showing papers by "Brian M. Wiegmann published in 2007"

Phylogeny and systematics of Diptera: Two decades of progress and prospects

Abstract: The Diptera, or true flies (mosquitoes, gnats, and house flies) comprise 12-15% of animal species, and are the most ecologically diverse order of insects, spanning ecological roles from detritivory to vertebrate blood feeding and leaf mining. The earliest known fossil Diptera are from the early Triassic 240 mya, and the order probably arose in the late Permian. The earliest brachyceran fossils are found in the late Triassic and earliest Jurassic, but the diversification of the extremely diverse Calyptrata (ca. 30% of described species) began in the late Creataceous. The monophyly of the order is supported by numerous morphological and biological characters and molecular data sets. The major lineages within the order are well established, and we summarize major recent phylogenetic analyses in a supertree for the Diptera. Most studies concur that the traditional subordinal group Nematocera is paraphyletic, but relationships between the major lineages of these flies are not recovered consistently. There is particular instability around the placement of the tipulids and their relatives and the families of the Psychodomorpha as traditionally defined. The other major suborder, Brachycera, is clearly monophyletic, and the relationships between major brachyceran lineages have become clearer in recent decades. The Eremoneura, Cyclorrhapha, Schizophora and Calyptrata are monophyletic, however the “Orthorrhapha” and “Aschiza” are paraphyletic, and it is likely that the “Acalyptrata” are also. Ongoing phylogenetic analyses that span the diversity of the order shall establish a robust phylogeny of the group with increased quantitative rigor. This will enable a more precise understanding of the evolution of the morphology, biogeography, biology, and physiology of flies.

Molecular phylogenetics of the Muscidae (Diptera : Calyptratae): new ideas in a congruence context

Abstract: Hypotheses about the evolution of Muscidae have long been the subject of continuous re-evaluation and reinterpretation. Current understandings of the relationships among these flies are based mainly on a single set of characters and are therefore questionable. Our understanding of muscid phylogeny thus needs greater support and further corroboration from additional suites of characters. In the current study, we analysed phylogenetic relationships among 24 species of muscid flies (18 genera and six subfamilies) using 2989 characters derived from sequences of mitochondrial (COI and COII) and nuclear genes (CAD and EF-1α). Data from each gene partition were analysed both in combined and separate phylogenetic analyses using maximum parsimony, maximum likelihood, and Bayesian inference. Support was found for the monophyly of the Muscidae in all analyses and for a sister-group relationship between Coenosiini and Phaoniinae. The latter group was placed in a clade with sampled species of Reinwardtiini and Cyrtoneurininae. The genera Ophyra and Hydrotaea were placed in the Muscinae and a sister-group relationship for Musca and Stomoxys was supported. Sampled species of Polietina form a monophyletic lineage, while Morellia was found to be paraphyletic. Combined analysis of gene partitions improved support and resolution for resulting topologies despite significant incongruence between data partitions found through application of the Incongruence Length Difference test.

Evolutionary patterns in the antR-Cor gene in the dwarf dogwood complex (Cornus, Cornaceae)

Abstract: The evolutionary pattern of the myc-like anthocyanin regulatory gene antR-Cor was examined in the dwarf dogwood species complex (Cornus Subgenus Arctocrania) that contains two diploid species (C. canadensis and C. suecica), their putative hybrids with intermediate phenotypes, and a tetraploid derivative (C. unalaschkensis). Full-length sequences of this gene (∼4 kb) were sequenced and characterized for 47 dwarf dogwood samples representing all taxa categories from 43 sites in the Pacific Northwest. Analysis of nucleotide diversity indicated departures from neutral evolution, due most likely to local population structure. Neighbor-joining and haplotype network analyses show that sequences from the tetraploid and diploid intermediates are much more strongly diverged from C. suecica than from C. canadensis, and that the intermediate phenotypes may represent an ancestral group to C. canadensis rather than interspecific hybrids. Seven amino acid mutations that are potentially linked to myc-like anthocyanin regulatory gene function correlate with petal colors differences that characterize the divergence between two diploid species and the tetraploid species in this complex. The evidence provides a working hypothesis for testing the role of the gene in speciation and its link to the petal coloration. Sequencing and analysis of additional nuclear genes will be necessary to resolve questions about the evolution of the dwarf dogwood complex.

Monophyly and phylogenetic relationships of Thereva and therevine genus-groups (Insecta : Diptera : Therevidae) based on EF-1α, 28S rDNA and mitochondrial 16S rDNA sequences

Abstract: Phylogenetic analyses using 28S rDNA, elongation factor (EF)-1α, and mt 16S rDNA sequences were performed to test the monophyly of Thereva Latreille. Two of the three Afrotropical Thereva species groups lack the genitalia characters that unambiguously diagnose Thereva in the Holarctic Region, but phylogenetic relationships among Thereva species groups and therevine genera are poorly understood. Using an extensive taxonomic sample (39 of the 62 therevine genera) and Thereva, sensu lato (15 spp.), simultaneous analyses of all three gene partitions recovered Nearctic and Palaearctic Thereva species in a well supported clade that includes the Afrotropical seminitida-group but excludes the Afrotropical analis- and turneri-groups. Stronger phylogenetic signal from the EF-1α partition, measured by the skewness statistic and proportion of total parsimony informative characters, dominated conflicting signal from the 16S partition and weaker, but more congruent, signal from 28S. Reducing the taxonomic sample in analyses of Therevinae reduced homoplasy, increased phylogenetic structure and partitioned Bremer support values and reduced incongruence with 28S for the 16S partition. Although molecular analyses yielded partial recovery of informal therevine genus-groups, morphological diagnoses of higher-level groups are poorly supported with the exception of Cyclotelini. The ‘Holarctic radiation’ refers to a diverse clade of genera closely related to Pandivirilia Irwin & Lyneborg and Acrosathe Irwin & Lyneborg widely distributed throughout the Holarctic Region that is the sister-group to Thereva, sensu stricto. Results from these analyses underscore the importance of male and female genitalia characters in recognising monophyletic groups and regional endemism in therevine diversification.