Meeting Abstract
P3.115 Jan. 6 Do Stable Isotope Turnover Rates in Ectotherm Tissues Change with Temperature? BOGARDUS, R.M.*; CHANG, Y.M.; HATCH, K.A.; Brigham Young University; Brigham Young University; Brigham Young University rob.bogardus@gmail.com
Stable isotope techniques are increasingly used as a means of detecting organisms� trophic position, changes in diet, and other ecological characteristics. However, most isotopic studies have been done with endothermic organisms, whose metabolic rates remain relatively constant with body temperature. Few such studies exist dealing with ectothermic animals, whose fluctuating body temperatures may influence isotopic turnover rates. We conducted a controlled laboratory study to examine whether or not temperature significantly affects the isotopic turnover rate of carbon in ectotherms. Three groups of house geckos (Hemidactylus frenatus) were placed in environmental chambers set at 24, 27, and 30 °C, respectively. During the 10-day acclimation period and for the first four days of the study period, they were fed exclusively on a diet of crickets (Gryllus bimaculatus), which had been raised on a C3 diet. After four days into the study period, the geckos� diet was changed to mealworms (Tenebrio molitor) raised on a C4 diet. Samples of uric acid were collected from each individual throughout the one-month study period. Samples were dried, prepared, and analyzed via IRMS. Using the resulting delta values, the half-life for δ13C in gecko�s uric acid was calculated as 2.5 days at 24 °C, 3.6 days at 27 °C, and 5.8 days at 30 °C. This apparently inverse relationship between temperature and turnover rate is highly interesting and bears further investigation.
