Maternal Effects Associated with Gestation Conditions in a Viviparous Lizard, Niveoscincus metallicus

Abstract

Viviparous squamates offer opportunities for exploring the importance of past maternalresources (yolk) and current resources (placentotrophy) to support embryonic growth duringgestation, and to optimize offspring fitness. Both thermal and nutritional environment of the motherduring gestation may be expected to be important in determining offspring fitness. Using a two-wayfactorial design, we have investigated possible interactions between food intake and thermalenvironment during gestation in the viviparous skink <i>Niveoscincus metallicus</i>. Among the femalesgiven restricted basking opportunities, fewer females gave birth, there was a significant increase ingestation length, and relative clutch mass was reduced due to smaller neonatal size; none of theseparameters were influenced by nutritional status. Neonates from mothers given restricted baskingopportunities were lighter, had shorter snout-vent lengths (SVL), and smaller fat bodies than neonatesfrom mothers given optimal basking opportunities; their postnatal growth rate (over eightweeks) was also significantly lower and they showed a reduced incidence of basking behavior. Therewere interaction effects between thermal regime and food supply for neonate SVL and neonatal fatbody weight. Sprint speed within 24 hours of birth was significantly increased in neonates frommothers given restricted thermal opportunities; however, for weeks 1-8 postnatally, there were nodifferences in sprint speed in offspring from any of the treatments. These results suggest that,contrary to our initial hypothesis, females maintained in nutritionally favorable conditions are unableto compensate for the gestational effects of a thermally poor environment. We now suggest that in<i>Niveoscincus metallicus</i> facultative placentotrophy may allow mothers to improve offspring fitnessby increasing neonatal fat body size.