Incubation temperature and sex affect mass and energy reserves of hatchling snapping turtles, Chelydra serpentina

Temperature during embryonic development irreversibly determines gonadal se x in many oviparous reptiles. Although embryonic temperature also influence s a number of other traits in these species. it is unclear whether such eff ects are primarily due to incubation temperature or to gonadal sex. Here we dissociated these normally confounding effects via hormonal manipulations of snapping turtle embryos (Chelydra serpentina), a species with temperatur e-dependent sex determination. We then ascertained temperature and xx effec ts on residual yolk mass, abdominal fat body mass: and total mass in neonat es shortly after hatching or after one month without feeding. Yolk mass was initially affected by incubation temperature. clutch identity, and rh;ir i nteraction, but not gonadal sex. Yolk mass was not influenced by any of the se variables 30 d after hatching. Fat mass was initially affected by temper ature and clutch, but not sex. Gonadal sex did, however, affect fat mass at 30 d of age as did temperature and clutch. Incubation temperature affected total mass in a complex manner. There were significant clutch by temperatu re interactions initially, bur no main effect of temperature. These effects changed so that the temperature effect was significant bur interaction eff ects il ere nor detected at 30 d of age. Repeated measures analysis of tota l mass after hatching and at 30 d of age indicated that turtles from lower temperatures lost more mass than turtles From higher incubation temperature s, and that females lost more mass than malts. These data indicate that som e hatchling traits were influenced directly by incubation temperature, wher eas others were independently affected by; gonadal sex. These results are c onsistent with a leading hypothesis for the evolution of temperature-depend ent sex determination.