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Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

A cladistic analysis of the world genera of the mayfly family Leptohyphidae is presented. Analyses of a matrix of 58 ingroup and 9 outgroup species and 119 morphological characters strongly supports the monophyly of Leptohyphidae and its sister-group relationship with Coryphoridae. Larval and adult taxonomic keys are provided to the 11 recognized extant genera. A synonymical listing, differential diagnosis, list of proposed synapomorphies, diagnostic illustrations, and notes on distribution and included species are given for each genus. The following new synonyms of genus Tricorythodes are proposed: Ableptemetes n. syn., Cabecar n. syn., Epiphrades n. syn., Homoleptohyphes n. syn., Macunahyphes n. syn., Tricoryhyphes n. syn. The former genus Asioplax is newly regarded as a subgenus of Tricorythodes. A species-level revision of North and Central American Leptohyphes is presented. A key to the 15 Leptohyphes species known as larvae is provided. In addition, detailed descriptions, diagnosis, and geographic distributions are given for all species of Leptohyphes known from North and Central America. Biogeographic analysis suggests that the family Leptohyphidae originated in South America, and that its North American species are the descendants of one or more ancestral species that crossed northward over the Panamanian land bridge. The results of this research clearly show that the mayfly family Leptohyphidae is a strongly supported monophyletic clade supported by five unique synapomorphies. Currently recognized genera are also strongly supported; however, little support was found for subfamilies. The sister family is clearly Coryphoridae, which is supported by three unique synapomorphies. Biogeographic analysis indicates that Leptohyphidae originated in South American, with at least five independent invasions from South America to North and Central America during the evolution of Leptohyphidae.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Oceanography." Includes bibliographical references (p. 160-173).

Thesis (Ph.D.) -- University of Texas at Arlington, 2008.

Thesis (Ph.D)--Virginia Commonwealth University, 2009. / Prepared for: Dept. of Biology. Title from resource description page. Includes bibliographical references.

Leafcutter ants (Atta spp.) are Neotropical herbivores that play important ecological roles, but are also notorious pests, causing millions of dollars in annual damage to agriculture across their range. Three species, A. cephalotes, A. sexdens, and A. laevigata, stand out as the most widespread and economically important. Two studies were conducted using these three species to better understand their biogeography and evolutionary history. First, using a maximum entropy niche-based modeling approach, locality information for these three species was used to (1) accurately describe the current geographic range of each species, (2) determine what factors limit their respective ranges, and (3) identify areas where each species is capable of becoming established. By comparing the model's predictions with published records and targeted surveys, a more accurate picture of the current ranges of each species was obtained. Areas in which a species does not currently occur, but that are predicted to be suitable, may reveal the ecological factors limiting the spread of these species. Such areas may also represent potential sites for invasion by these ants, with potentially devastating results. Second, these species were used to test the leading biogeographic hypotheses on the origins of high Amazonian diversity, an issue that remains unresolved despite much research. The hypotheses are the riverine barrier, Pleistocene refugia, and marine incursion hypotheses, each of which has been tested almost exclusively on vertebrates. A comparative, molecular phylogeographic approach was combined for the first time with paleodistribution modeling for the last glacial maximum to test these hypotheses on an insect. All analyses rejected the predictions of the riverine barrier hypothesis for each species. Tests of gene tree topology could not reject the refugia hypothesis for A. sexdens, while population-genetic and historical demography analyses failed to reject both the refugia and marine incursion hypotheses for all three species. However, coalescent-based estimates of population divergences for each species suggest that current population structure formed recently, suggesting that Miocene marine incursions have not promoted diversification in these species. Therefore, of the hypotheses examined, only the Pleistocene refugia hypothesis can explain the current population structure of Amazonian leafcutter ants.

New Zealand is a continental island surrounded by deep-ocean, with a complex system of currents and oceanographic anomalies that may serve to isolate populations of coastal marine organisms. In particular Cook Strait is a 26 km wide body of water separating the North and South Islands which is characterised by complex interactions of tides and converging water masses. Cook Strait is a geologically recent formation that may also impart an historical influence on the biogeographic distribution of coastal marine taxa. In order to investigate the phylogeographic structure of coastal marine taxa around New Zealand's coastline and to investigate the processes that may contribute toward this genetic structure, I analysed mitochondrial DNA genes from limpet species of the Cellana genus. Phylogenetic analyses of the ribosomal 12S and 16S DNA genes showed that C. ornata may approximate the founding lineage to New Zealand, but these genes were unable to resolve between contrasting biogeographic hypotheses about the origin of Cellana in New Zealand. Intraspecific analyses of the mitochondrial cytochrome b gene from populations throughout the biogeographic range of Cellana ornata, C. radians and C. flava showed concordant genetic discontinuity at Cook Strait. Further analyses suggest that allopatric fragmentation and restricted gene flow have caused significant genetic differentiation between populations of the North and South Island. Demographic expansion was also identified for C. radians. The influence of contemporary nearshore currents and sea surface temperature was assessed using the mitochondrial cytochrome b gene for C. radians and C. ornata. Low levels of genetic differentiation between populations corresponding to 'current-zones' suggests that contemporary oceanic processes may be contributing to the genetic pattern observed for these species. However, the shallow divergence between haplotypes and populations restricted thorough investigation of contemporary gene flow. Genealogical concordance across co-distributed marine taxa of New Zealand also lends support to the historic association of genetic and species discontinuities with recent geological changes, such as sea level fluctuations.

Thesis (Ph. D.)--Department of Geology, University of Adelaide, 1990. / Includes other papers published by the author. Includes bibliographical references (p. 620-629).

Thesis (Ph. D., Bioinformatics and Computational Biology)--University of Idaho, September 2007. / Major professor: Larry J. Forney. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.