Meeting Abstract

P3.67  Monday, Jan. 6 15:30  Pre-heating to sublethal temperature did not improve thermal limits of lizard embryos LEVY, O; SMITH, C; BOATENG, K; KUMAR, D*; ANGILLETTA, MJ; Arizona State University, Tempe, AZ 85287, USA; Arizona State University, Tempe, AZ 85287, USA; Arizona State University, Tempe, AZ 85287, USA; Arizona State University, Tempe, AZ 85287, USA; Arizona State University, Tempe, AZ 85287, USA levyofi@gmail.com

Future climates will impose acute heat stresses that should be most stressful to embryos, which cannot behaviorally thermoregulate as effectively as juveniles and adults. We studied the heat tolerance of lizard embryos (Sceloporus undulatus) from populations in New Jersey and South Carolina. A previous experiment showed that these embryos could not survive a single brief exposure to 42°C, suggesting a threshold for thermal tolerance. However, many animals can adjust their thermal tolerance through acclimation. To explore the potential for heat hardening by embryos, we exposed eggs to either a peak of 35°C (control) or 40°C (pre-heated) prior to exposing both groups to either 42° or 44°C. Survival was inferred daily from measurements of heart rate. We expected that embryos pre-heated to 40°C would survive exposure to higher temperatures whereas control embryos would not. However, neither pre-heated nor control embryos survived a single brief exposure to 44°C and all embryos survived a similar exposure to 42°C. Rapid heat hardening does not appear to be a mechanism by which lizards will cope with thermal stress during embryonic development.