59-6 Friday, Jan. 5 11:30 - 11:45 Exposure to fluctuating temperatures at different intervals during incubation influences embryonic growth and hatchling morphology in Chelydra serpentina. FINKLER, MS; Indiana Univ. Kokomo email@example.com http://www.iuk.edu/faculty_staff/mfinkler/research.php
Fluctuating diurnal temperatures influences incubation duration as well as the sex, size, and locomotor performance of hatchling turtles. However, given that different stages of development differ in their degree of thermal sensitivity, exposure to thermal fluctuations during some developmental intervals (e.g., early development) may have greater impact on hatchling phenotype than during other developmental intervals (e.g., late development). I incubated snapping turtle eggs under five different thermal regimes with the following combinations of constant temperature (25°C) and diurnally fluctuating temperature (25±2°C): constant temperature throughout incubation (Constant), fluctuating temperature throughout incubation (Fluctuating) and fluctuating temperature only during the first 21 days of incubation (1st Trimester) Days 22 to 42 (2nd Trimester), or from Day 43 to the end of incubation (“3rd Trimester”) with constant temperatures at other intervals. Exposure to fluctuating temperatures accelerated embryonic growth and development rates compared to constant incubation temperatures at all intervals examined. Hatchlings from the Fluctuating treatment hatched earlier and had longer carapace and plastron lengths than did those from the Constant treatment or from the 3rd Trimester treatment. Eggs in the 1st Trimester treatment hatched sooner than did those in both the 3rd Trimester and Constant treatments. There was no difference in hatchling dry mass among any of the incubation treatments. These findings indicate that diurnal fluctuations in temperature accelerate growth and influence hatchling morphology. Moreover, fluctuating temperatures during early incubation appear to have a more pronounced effect on incubation duration than similar fluctuations during late incubation.