Date of Award
2001
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Biology
Abstract
Animals communicate in many different ways using a variety of signals to send information to conspecifics and heterospecifics. These systems consist of at least two individuals, signalers and receivers. Signalers produce and physiologically control the production of signals and send the signal into the environment. Receivers obtain signals via sensory receptors, process information in the central nervous system, and respond in some manner. Selective forces could act on any one, or a combination of, these factors to lead to sex and species differences. Thus, to properly study the evolution of these systems, evolutionary biologists must examine multiple levels. I have studied both the production and physiological control of an exaggerated male signal, and the male and female responses to a signal in a phylogenetic context. The signal is a pair of abdominally located blue patches present in most males of Sceloporus lizards. Two derived character states also exist, male loss of the signal (both males and females have entirely white abdomens) and female gain (both males and females have blue abdominal coloration). My research indicates that blue abdominal coloration is produced by the presence of melanin in the dermal layer and that abdominal coloration is controlled by the elevation of the steroid hormones testosterone and 5α-dihydrotestosterone. In addition, male Sceloporus lizards appear to respond to this signal in the same manner regardless of the presence or absence of this signal and females respond to this signal in the same manner.
Recommended Citation
Quinn, Vanessa S., "Proximate And Ultimate Factors Contributing To The Variation In A Sexually Dimorphic Signal In Sceloporus Lizards" (2001). All-Inclusive List of Electronic Theses and Dissertations. 1042.
https://scholars.indianastate.edu/etds/1042