Phylogenetic Utility of Two New Nuclear Genes, Opsin and CAD, within the stiletto flies (Diptera: Therevidae)

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Title: Phylogenetic Utility of Two New Nuclear Genes, Opsin and CAD, within the stiletto flies (Diptera: Therevidae)
Author: Hill, Hilary Nan
Advisors: Brian M. Wiegmann, Committee Chair
Lewis L. Deitz, Committee Member
Edward L. Vargo, Committee Member
Abstract: A need for multiple phylogenetic markers to reconstruct evolutionary relationships is increasingly apparent within both the Therevidae and insect systematics as a whole, especially markers that can accommodate the immense species diversity that arose during the Mesozoic (~65-250mya). Phylogenetic trees are often best reconstructed using datasets from distinct sources and from character sets that have been under different selective pressures. Many recent insect systematics studies use various combinations of markers from multiple genomes, morphology, and biogeography. Nuclear genes, particularly protein-encoding genes that are highly conserved and low copy-number, are increasingly attractive as phylogenetic markers, and there is a recent concerted effort to find and increase access to new nuclear genes. Chapter one of this study investigates the phylogenetic utility of opsin, a new multiple copy nuclear protein-encoding gene in the dipteran family Therevidae. The present analyses of nucleotide sequence data of opsin reconstructed a therevid phylogeny that is partially concordant with previous classifications which demonstrates that opsin may have some limited utility as a phylogenetic marker within the Therevidae and closely related Diptera, but also shows that opsin may be better used in combination with other molecular markers or morphological data sets. Phylogenetic analyses of opsin at multiple levels within insects supports these results, but also reveals the significant obstacles in technical manipulation of the gene and in the interpretaion of ortholog/paralog relationships. In the second chapter two new nuclear, protein-encoding genes, opsin and CAD, in combination with EF-1a and 28S rDNA, are applied to reconstruct evolutionary relationships among the major lineages of Therevidae for which previous molecular evidence has been insufficient. The analyses of 28S rDNA, EF-1a, opsin, and CAD nucleotide sequences provide phylogenetic resolution that is highly concordant with the current therevid classification. The analyses also reveal that the phycine tribe Xestomyzini is monophyletic and could represent a major therevid clade. The new molecular dataset generated from this study can be used to build a larger dataset and can also be used in conjunction with a morphological dataset that is currently being generated within the therevid PEET project.
Date: 2003-07-07
Degree: MS
Discipline: Entomology

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