During speciation, populations become spatially separated from each other by biotic or abiotic factors, and this leads to genetic divergence and reproductive isolation. Here, I study the process of speciation and the patterns resulting from this process in the chorus frogs (Pseudacris). I first lay the foundation for this work by constructing phylogenies based on molecular data. I then address broad-scale questions regarding the abiotic factors thought to drive speciation. I examine evolution of reproductive signals within a phylogenetic context, and finally, I address fine-scale questions regarding the completion of reproductive isolation in contact zones between recently-evolved species. In chapter 1, I estimate the phylogenetic relationships across the genus Pseudacris. I find that several species of unclear status (regilla, cadaverina, crucifer, ocularis) belong to this genus, and that P. ocularis is the sister species of P. crucifer. In chapter 2, I examine the phylogeography of a clade within Pseudacris, the trilling chorus frogs. I find support for at least nine species and delineate their geographic distributions. In chapter 3, I test geological and climatic hypotheses proposed to drive speciation in North American flora and fauna. By estimating divergence times in the trilling chorus frogs and correlating these divergences with timing of geologic events, I find that marine inundation of the Mississippi Embayment may have caused speciation in this group. Additionally, I find that climatic events led to reduced genetic variation rather than divergence within species. In chapter 4, I study the evolution of acoustic signals of all species of Pseudacris. Using a comparative method approach, I find that physiologybased call variables are more evolutionarily labile than morphology-based call variables. In addition, I find that sympatric signals are more different than allopatric signals, suggesting that these frogs have partitioned the acoustic niche. In chapter 5, I examine evolution of reproductive isolation between two chorus frog species in sympatry. I find that male signals show a repeated pattern of divergence in sympatry, and that different axes of the signal diverge in different populations, suggesting that heterospecific overlap may lead to reproductive isolation among conspecific populations. I also find that female preferences have evolved in sympatry, suggesting that divergence in the contact zone is due to reinforcement.

No description available.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on February 28, 2008) Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago. / Cover title. Reprinted from the Journal of comparative neurology, vol. 9, no. 2, June 1899. Bibliography: p. 107-109.

Thesis (Ph. D.)--University of Chicago. / Cover title. Reprinted from the Journal of comparative neurology, vol. 9, no. 2, June 1899. Bibliography: p. 107-109.

Thesis (M.S.)--Marshall University, 2004. / Title from document title page. Document formatted into pages; contains vi, 103 p. including illustrations and maps. Includes bibliographical references (p. 100-103).

Thesis (Ph. D.)--University of Oregon, 2005. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 76 - 80). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (M.S.)--Marshall University, 2002. / Includes bibliographical references (p. 34-40). Online version available in PDF format.

The purpose of this study was threefold. The literature concerning parasites of A. crepitans was to be brought up to date. Contributions to the general body of knowledge pertaining to the parasitic fauna of host specimens of A. crepitans and specifically those found in Denton County, Texas, were to be made. Finally, specimens found parasitizing host specimens of A. crepitans were to be preserved and classified.

The northern leopard frog (Rana pipiens) is a species that depends on landscape connectivity to complete its lifecycle. However, due to historic and present anthropogenic landscape changes, this species encounters a variety of agriculture fields during migratory and dispersal movements. These landscape changes have potential to affect habitat connectivity for these frogs and may interfere with the species? life-cycle needs. Differing land-cover types have varying effects on movement, desiccation and predation of the northern leopard frog, which in turn affect the frog?s ability to survive. Through creation and use of an agent-based model that can simulate individual frog movement on a modeled landscape, I explored habitat connectivity in the prairie-pothole region. I used northern leopard frog movement and desiccation data collected from two summers of field work to inform my modeled scenarios. The model I developed allows for the exploration of habitat connectivity under various patterns of land-cover change. / U.S. Geological Survey Climate Research and Development Program / North Dakota State University (NDSU)