Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 177-189). Available also in a digital version from Dissertation Abstracts.

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Stridulation in the waterbug genus Cenocorixa was studied in the field and experimentally in the laboratory. It was shown that both males and females stridulate. The stridulatory signals, analysed by use of a sound spectrograph, were shown to be species and sex specific, differing in temporal pattern of pulses, pulse rate, pulse structure, and signal length. It was shown that the annual rhythm of stridulation in both male and female is correlated with sexual maturity. Males will spontaneously stridulate when there is mature sperm in the testes, and this occurs in spring, early summer, and late fall. Females do not stridulate spontaneously, but can be induced to stridulate when they have chorionated eggs in the lateral oviducts, but no sperm in the receptaculum seminis; they are sexually mature only in the spring and early summer. Stridulation was shown to be important in behavior leading to successful copulation. Male stridulation functions as a calling signal facilitating pair-formation by attracting conspecific females, and as an agonistic signal serving to space out individuals. Males will answer almost any stridulatory signal, but only calls from a conspecific female initiate searching behavior. Receptive females respond to stridulatory stimuli from conspecific males by stridulating, and successful copulations were observed only when preceded by such signal recognition; female stridulation functions as an agreement signal. Stridulation serves as a premating isolating mechanism in Cenocorixa. However, it is not the only isolating mechanism, but is reinforced by geographic and ecological isolation in a number of cases. The Corixidae, since they mostly have only a single stridulatory signal that can function in at least two contexts, are considered to represent a primitive stage in evolution of stridulatory signals: a stage in which functional diversification of signals is just evolving. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (Ph.D.)--University of Missouri-Columbia, 2006. / 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 26, 2007) Vita. Includes bibliographical references.

Thesis (M.S.)--Florida State University, 2003. / Advisor: Dr. Frank Johnson, Florida State University, College of Arts and Sciences, Dept. of Psychology. Title and description from dissertation home page (viewed Sept. 24, 2003). Includes bibliographical references.

The evolution of mating signals has long interested biologists because changes in mating signal production and/or reception can lead to reproductive isolation and speciation. Here, I examine the evolution of the male mating signal (the advertisement call) and the female preference for this call in the Western Toad, Bufo boreas. Call surveys and a morphological study for the occurrence of vocal sacs, which are necessary for producing these calls, reveal that only populations in the northeastern corner of this species’ range produce long, high-amplitude advertisement calls. This is the first study to report among-population variation in the presence of the major mating signal in any animal. Although populations vary in whether or not males call, phonotaxis tests demonstrate that female B. boreas in calling and non-calling populations have the preference for this call. Phylogenetic analyses indicate that the call was lost in the ancestor to modern B. boreas and then secondarily re-evolved in the ortheastern populations. Bufo boreas is one of many toad species that inhabits the Nearctic region. I use phylogenetic analyses of large and small subunit mitochondrial ribosomal DNA sequences to examine the phylogenetic relationships among Nearctic toad species and test previously proposed biogeographic hypotheses for the colonization history of the Nearctic region. This work indicates that the Nearctic Bufo are monophyletic and result from a single colonization event from the Neotropics. Further, fossil and paleogeographic data suggest that this colonization occurred prior to the formation of a contiguous land bridge between the Neotropic and Nearctic regions. Many of the individuals examined in the Nearctic toad study had previously been sequenced for the same gene region. A surprising number of errors were found in the earlier sequences and attributed to the method of sequence generation. In my final chapter, I review the causes and consequences of sequencing error and present a novel method that uses sequence conservation information to detect errors. This approach is exemplified with the unique dataset of replicated sequences, and resources for easily implementing this approach are made available on the Comparative RNA Web Site (http://www.rna.ccbb.utexas.edu/). / text

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Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.