Discipline: Biological Sciences
Victoria A. Buskey - Virginia State University
Co-Author(s): Shericia C. Campbell, Virginia State University, VA
Global climate changes are causing widespread population and species extinctions. These extinctions are based on the inability of species to adapt either physiologically or behaviorally to the rate of rising temperatures. Altitude, one determinant of thermal environment, display an inverse relationship between altitude and temperature. Ectothermic species, whose body temperatures result from ambient air temperatures and thermoregulation behavior such as basking or morphological attributes (e.g., size, shape or color), may have fixed thermal preferences based on internal physiological reactions. This may limit their ability to adapt to environmental climate changes. However, species with greater altitudinal distributions subject to broader temperature ranges should show a wider variance of thermal preferences. If the variation in thermal preferences is primarily environmentally and not genetically determined, then species with a range of thermal preferences should have a greater ability to tolerate climate change. We used Slevin?s bunchgrass lizard, Sceloporus slevini, a species that occurs at both low and high elevations, to test the hypothesis that thermal preference of S. slevini at high elevations is lower than the thermal preference of those at lower elevations. Lizards from high and low elevations at two different site in southeast Arizona were collected by hand and transported to the laboratory. Data collected from each individual were: GPS coordinates, snout-vent length, mass, sex and female reproductive state (gravid or non-gravid). To test thermal preferences we used a test apparatus consisting of a thermal gradient created by suspending a 100W incandescent light bulb at one end of a 1.22m long chamber with a fluorescent light suspended over the other end. We used a sample size of 66 lizards to determine temperature preferences. Individual temperature preferences were determined by averaging five body temperature measurements taken over a 60 minute period. A two-sample T-test was used to determine if significant differences exist between populations. Significant differences in preferred body temperatures were found between high elevation and low elevation lizards (t = -4.03, P = 0.002, df = 11). High elevation lizards had mean body temperatures of 30.12oC compared to low elevation lizards with mean body temperatures of 33.94oC. The support of the hypothesis that thermal preference differed between high and low elevation populations suggest that this species may have a broad range of thermal tolerance. If so, species with similar thermal preference ranges may be buffered against extinction. Future research will determine if this variation is genetically fixed or environmentally determined and explore the relationship of temperature preference to optimal escape speeds, sex differences and whether gravid and non-gravid females display different temperature preferences.
Funder Acknowledgement(s): Funding was provided by a National Science Foundation HBCU-UP grant to C. d'Orgeix
Faculty Advisor: Christian, firstname.lastname@example.org
Role: I participated in field research and data analysis.