Effects of maternal identity and incubation temperature on Snapping Turtle (Chelydra serpentina) growth

Abstract

Summary Individual variation in physiological traits may have important consequences for offspring survival rates and adult fitness. Variance in offspring phenotypes is due to interindividual differences in genotype, environment or maternal effects. This study examined the contributions of family identity, egg incubation environment and maternal effects to individual variation in growth rates in the common Snapping Turtle, Chelydra serpentina. The growth rates of 254 individuals, representing 24 clutches, were measured for approximately 6 months. Mean growth rate for all individuals was 7·21 mg g−1 day−1 (= day−1) (SE = 0·12 day−1, range =−3·70–13·03 day−1). Growth rates varied significantly among clutches, ranging from 5·76 to 9·20 day−1, indicating that family identity, and possibly genotype, significantly affects posthatching growth. In general, larger eggs produced larger hatchlings, and individuals that were larger at birth were larger at 175 days of age. Thus, maternal effects were significant throughout the entire growth measurement period. In contrast to results from previous studies, egg incubation temperature did not significantly affect individual growth. Because all individuals received similar treatments and were in similar environments posthatching, our results suggest that there is a genetic component to growth rate, but that egg incubation temperature does not affect growth.