Placement of Micropezinae (Micropezidae) on the Diptera Tree of Life: a molecular phylogenetic approach

This thesis is divided into two parts centred around the higher relationships of Micropezinae (Diptera: Micropezidae). The first chapter is a multi-gene molecular phylogenetic analysis of Nerioidea (Diptera: Schizophora). The relationships of the four families of Nerioidea (Micropezidae, Neriidae, Pseudopomyzidae, and Cypselosomatidae), as well as the internal relationships and subfamilial classification of Micropezidae, have been the source of considerable debate. These relationships are tested using 13 genetic loci sampled for 77 Nerioidea species and 39 outgroup taxa from across Schizophora and analyzed using Bayesian Inference and Maximum Likelihood. Nerioidea was recovered as monophyletic with strong support, as were each of the four families within, with Micropezidae being returned as the sister group to the remaining Nerioidea. Internal relationships of Micropezidae included strong support for each of the subfamilies with the exception of Eurybatinae, which was recovered as polyphyletic, with the Metopochetini forming a well-supported sister group relationship with Micropezinae. The remaining Eurybatinae were well-supported as the sister group to Taeniapterinae. The implications for the taxonomy and classification of Micropezidae subfamilies are addressed. The tribe Metopochetini is elevated to subfamily rank (Metopochetinae). The second chapter of this thesis aims to clarify the higher relationships of Nerioidea within Schizophora. The relationships between superfamilies of Schizophora have proven difficult to establish on the basis of morphology and molecular data to date, resulting in unstable classifications and evolutionary hypotheses. Using a supermatrix composed of previously published DNA sequences from 23 genetic loci sampled across 2300 schizophoran taxa, the relationships of Schizophora are estimated using Maximum Likelihood with multiple data subsampling and substitution model strategies. Two preferred trees were recovered which are strongly congruent with both morphological and genomic approaches, signifying supermatrix analyses represent a viable alternative for elucidating schizophoran relationships. Taxon availability and sampling, particularly among Carnoidea and Sphaeroceroidea, remain a significant barrier to a fully resolved phylogeny of Schizophora. Higher relationships of Schizophora were found to be highly sensitive to taxon sampling and substitution model parameters, while there is significant evidence of differential phylogenetic signal between nucleotide sites and taxonomic lineages, indicative of heterotachy. Implications for the future of Schizophora systematics are discussed.