No description available.

Graduate

Thesis (Ph. D.)--Cornell University, 1902. / Cover title. "Reprinted from the Biological Bulletin, vol. IV, no. 2, December 1902."

Thesis (M.S.)--Duquesne University, 2003. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 99-109) and abstract.

This paper deals with the complete skeletal anatomy ot Bolitoglossa rufescena (Cope). All parts are figured and described. In addition to this many of the main skeletal parts of Bolitoglossa platydactyla (Cuvier) Bolitoglossa occidentalis Taylor, and Bolitoglossa flaviventris (Schmidt) are described and figured. A comparison of the following parts of the above mentioned salamanders is presented: skull, atlas, ninth trunk vertebra, sixth caudal vertebra, carpals, tarsals and digits. The similarities and differences are pointed out as they appeared to the author. The relationship and specialization ot these species is discussed rather briefly.

Salamander courtship coordinates the exchange of gametes. Plethodontids have evolved an elaborate means by which this is done. Throughout the family Plethodontidae a tail-straddling walk is performed to orchestrate the transfer of sperm. Typically this behavior is linear, however in the genus Aneides there are exceptions. In the genus Aneides there are two species that have a circular tail-straddling walk; others perform the highly conserved linear tail-straddling walk. I observed courtship in three species of Aneides and used accounts of others to discern which members possessed circular tail-straddling walk and used a phylogeny to map the courtship characters found in the courtships of the members of the tribe plethodontini. / Graduation date: 2003

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 124-140). Also available on the World Wide Web.

No description available.

My dissertation focuses on the evolutionary forces that have shaped the chemical signaling system of plethodontid salamanders. Pheromones mediate two phases of plethodontid reproduction: mate attraction prior to courtship and female persuasion during courtship. Substrate-borne chemical signals are believed to play an important role in mate attraction for these animals. A behavioral assay of sex- and species-specific odor preferences in closely related species of Plethodon indicates that: (1) there is asymmetry on the receiver side of the system, wherein male salamanders invest more energy searching for mating partners than do females; (2) substrate-borne chemical signals are sexually dimorphic and male preference strongly favors the female odor versus the male odor; (3) females of allopatric salamander species have evolved distinctive chemical cues; and (4) female chemical signals of sympatric species are divergent and may play a role in sexual isolation. Sexual persuasion is another phase of plethodontid reproduction that is mediated by chemical signals. Plethodontid Receptivity Factor (PRF) is a proteinaceous pheromone that is produced by the male and delivered to the female during courtship. Female receptivity increases following application of this pheromone. PRF is a recent innovation of the male courtship signal, originating in eastern Plethodon (~27 MYA). Codon-substitution models indicate that several amino acid sites along the PRF protein have experienced positive selection. Structural modeling suggests that many of these selected residues are important for receptor binding. Adaptive change in this pheromone is likely driven via a coevolutionary association with female receptors. The male plethodontid courtship signal, however, is comprised of multiple chemical components. I investigate micro- and macro-evolutionary divergence in plethodontid chemical communication by surveying two additional pheromone component genes, PMF and SPL. Like PRF, regions of the PMF and SPL genes have experienced adaptive change. At least one of these components (SPL) has been retained in the signaling system for ~100 MY. However, significant differences in the composition of the courtship pheromone are evident in some plethodontid lineages. It appears as if at least two lineages (Desmognathus and eastern Plethodon) use different major pheromone components and yet achieve the same behavioral response in the female (increased receptivity). / Graduation date: 2005

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