Effects of early postnatal environment on phenotype and survival of a lizard.

Nutritional and thermal regimes experienced early in life can strongly influence offspring quality and ultimately adult life histories, especially in ectotherms. However, the importance of the interaction between diet and temperature during postnatal development and the effect on offspring quality are unknown. We compared offspring quality (size, shape, speed, behavior, and survival) of juvenile McCann's skinks (Oligosoma maccanni) housed outdoors under variable thermal conditions (under shelter, but exposed to daily and seasonal variations in light and temperature) with those housed indoors under more stable thermal conditions (controlled temperatures providing 30-40% more basking opportunity) and with a control group (open field conditions). For those caged in captivity (indoors and outdoors), we also compared outcomes between those fed a restricted diet and those fed ad libitum. By comparing individuals raised under different environmental regimes, we aimed to determine whether direct effects of temperature or indirect effects of food supply are more important for offspring quality. Individuals provided with food ad libitum grew faster, and attained larger sizes than those raised on a restricted diet or in the field. Activity rates were higher in individuals exposed to stable rather than variable thermal conditions. Survival post release in the field was highest for larger neonates, and lowest in individuals raised under stable thermal conditions and a restricted diet. We found little evidence for effects of an interaction between feeding and thermal regimes on most factors measured. However, the conditions experienced by young animals (especially diet) do influence important traits for population persistence, such as survival, and may influence key reproductive parameters (e.g., age and size at maturity), which could have implications for conservation management. Further research, including the ultimate influence of early environmental conditions on fecundity and life expectancy, is urgently needed.