Doctor of Philosophy, The Ohio State University, 2015, Evolution, Ecology and Organismal Biology

Communication between potential mates is of vital importance to the fitness of many taxa, allowing individuals to find one another, as well convey and receive information important in assessing a suitable mate. Signals involved in sexual communication can be transmitted through visual, vibrational and chemical modalities, with chemical communication being the oldest and most widespread. The ability to detect visual and vibrational cues often occurs across a range of inputs, while chemical communication has the potential for much higher specificity, as only those receivers possessing chemosensory cells attuned to the compounds used will be able to detect their presence. The detection and integration of multimodal signals into a behavioral response has been extensively studied in the Schizocosa ocreata (Hentz 1844) wolf spider (Lycosidae) model system. In this ground dwelling species, males respond to substrates containing female chemical signals with visual and vibratory courtship displays. While this response has been well characterized, the chemical identity of these signaling compounds is currently unknown, and pheromone identity has been understudied across spiders as a whole. The behavioral response of male S. ocreata to conspecific chemical signals has primarily been studied in the context of substrate bound female cues, though past studies have suggested that chemicals produced by conspecific male competitors may inhibit male courtship behavior, and have even suggested a role for olfaction.We further examined the role olfaction plays in male detection and location of females, and while we found no evidence that males are utilizing olfaction to find mates, we did observe behavioral changes to conspecifics of both sexes, and a reduction of activity in the presence of volatile cues from a predator. At levels of competitor cues that males are expected to encounter in nature, we found no evidence that male-male inhibition occurs in this species. In examining male r (open full item for complete abstract)

Committee: J. Andrew Roberts (Advisor); Susan Gershman (Committee Member); Roman Lanno (Committee Member) Subjects: Behavioral Sciences; Biology; Ecology

PhD, University of Cincinnati, 2009, Medicine : Pathobiology and Molecular Medicine

Genetic techniques requiring recombination in the pathogenic fungus, Histoplasma capsulatum, are currently limited because the organism rapidly loses mating ability in culture. The studies presented in this body of work sought to determine molecular mechanisms that regulate mating in H. capsulatum, as a step toward preventing or reversing the loss of mating ability in cultured strains. Fungal mating loci are characterized by the presence of transcription factors that regulate mating, and some mating loci contain multiple genes involved in the mating response. We identified the mating locus of H. capsulatum and showed that the transcription factors MAT1-1-1 and MAT1-2-1, present at the MAT1-1 and MAT1-2 idiomorphs of the mating locus, respectively, are transcriptionally responsive to mating conditions. To identify additional components of mating regulation in H. capsulatum, we used syntenic analysis to identify a putative alpha pheromone. The alpha pheromone was found to be produced by MAT1-2 mating type organisms under mating conditions, and it was determined that organisms of MAT1-1 mating type respond to the alpha pheromone. UC1, an H. capsulatum strain that gained the ability to form empty cleistothecia with a mating partner after insertional mutagenesis, was used to determine additional molecular mechanisms that contribute to cleistothecia formation. Silencing HMK1, a predicted MAP kinase involved in the pheromone response MAP kinase pathway, had no effect on cleistothecia formation by UC1; however, Pkc1 activity was linked with pheromone production in this strain. These studies showed that the H. capsulatum mating locus transcription factors and the alpha pheromone play a role in mating, similar to that of other fungi. Pkc1 activity, however, is only indirectly linked to mating ability in other fungi, opening up areas for future studies determining the role Pkc1 plays in regulation of mating and mating competency in H. capsulatum.

Committee: George Smulian MD (Committee Chair); George Deepe MD (Committee Member); Judith Rhodes PhD (Committee Member); Jason Blackard PhD (Committee Member); Eric Gruestein PhD (Committee Member) Subjects: Biology

Doctor of Philosophy, Case Western Reserve University, 2010, Biology

Molecules evaporating from objects are carried by air creating a plume of odor that many animals use to find ecologically important resources. Odor plumes are dominated by turbulence (fluctuations in air velocity) when carried long distances, which results in a patchily distributed odor with high and low concentration areas surrounded by clean air. The consequence of this patchy distribution is that concentration itself is not a reliable directional signal for navigation towards a source. Therefore, many insects orient to the direction of air flow to aim themselves toward a source. When tracking species-specific sex pheromone within an experimental wind tunnel, the males of the Tobacco Hornworm Moth (Manduca sexta) fly and the American Cockroach (Periplaneta americana) walk, orienting themselves upwind. These males alter their tracking behavior in response to changing flow and odor signals caused by structures designed to mimic natural turbulence. Flow and odor signal characterizations with hot wire anemometry and electroantennograms explain those differences in the behavior of walking and flying trackers; walking cockroaches appear to respond better to spatial flow information and distinct odor/clean-air boundaries while flying moths appear to respond better to temporal flow information and odor plumes with larger cross sections. However, my results also show that cockroaches may be capable of a more complex odor tracking strategy than a purely spatial comparison between their two antennae because unilaterally antennectomized cockroaches can track a plume and find an attractive odor source. Computer simulations show how purely spatial or temporal control algorithms perform in different turbulent odor distributions, and are then used to test hypotheses about how flying and walking trackers utilize flow and odor signal information differently to find a source. The changes in behavior of insects tracking odor using different modes of locomotion in different environmen (open full item for complete abstract)

Committee: Mark A. Willis PhD (Advisor); Christopher A. Cullis PhD (Committee Chair); Hillel J. Chiel PhD (Committee Member); Debra Wood PhD (Committee Member); Roy E. Ritzmann PhD (Committee Member); Edward B. White PhD (Committee Member) Subjects: Behaviorial Sciences; Biology