WATKINS, T.B.; AWANTANG, G.; EAGAR, T.C.; Macalester College, St. Paul MN: Effects of Pre- and Post-Hatching Temperature on Locomotor Performance and Thermal Preference of Tadpoles

The temperature at which the eggs of ectothermic vertebrates incubate can influence several phenotypic traits of offspring. Most studies of this phenomenon have examined only the direct effects of incubation temperature, and have ignored interactions between incubation temperature and post-hatching developmental temperature. We previously demonstrated in wood frogs (Rana sylvatica) that warm egg incubation produces slower-swimming tadpoles and showed that the detrimental effect of warm incubation may be eliminated if hatchlings from warm eggs select cooler post-hatching temperatures than tadpoles from cool eggs. In the present study we incubated green frog eggs (Rana clamitans) at 20 and 26C, and reared the resulting offspring for several weeks at 20 and 26C in a factorial design. For both hatchlings and young tadpoles we estimated swimming performance from high speed video records and temperature preference in a laboratory thermal gradient. Hatchlings from the 20C incubation treatment had significantly lower preferred body temperatures than those from the 26C incubation treatment (25.8 � 2.7 vs. 28.3 � 1.8 [mean,SD], P < 0.001). We will relate this finding to differences in swimming performance and compare hatchlings to later-stage tadpoles. Funding was provided by Howard Hughes Medical Institute to TCE.