AN EXPERIMENTAL STUDY OF THE INFLUENCE OF EMBRYONIC WATER AVAILABILITY, BODY SIZE, AND CLUTCH ON SURVIVORSHIP OF NEONATAL RED-EARED SLIDERS, TRACHEMYS SCRIPTA ELEGANS

The period during which neonatal aquatic turtles migrate from their nests to the water is a critical stage, as mortality is high. Thus, the patterns and targets of natural selection involving the turtles are important to investigate. To evaluate these questions, we incubated eggs of red-eared slider turtles (Trachemys scripta elegans) and overwintered the resulting hatchlings under ecologically-relevant, common-garden conditions in the laboratory. We then performed an experimental release of 358 neonates in the field to investigate the possible effects of (1) water potential of the substrate on which the eggs were incubated (−60 and −100 kPa), (2) body size at the time of release, and (3) clutch of origin on short-term posthatching survivorship. Only clutch significantly affected survivorship in this field study. The lack of an effect of body size on survival may be due to substantially drier weather during the migration period than in previous and subsequent experiments, which may have led to atypical burying behavior by the turtles.