ROBBINS, T.R.*; WARNER, D.A.; University of South Florida; The University of Sydney: Fluctuations in the incubation environment: Does the pattern or magnitude influence egg survival and hatchling phenotypes in a lizard?

Environmental and maternal factors can shape offspring phenotypes in ways that could influence offspring survival and fitness. Most studies that evaluate environmental effects on offspring phenotypic variation use environmental conditions that remain constant throughout the duration of the experiment despite the fact that fluctuations in environmental parameters (i.e., temperature or moisture) occur under natural situations. In a laboratory experiment, we investigated the effects of fluctuating moisture regimes during incubation on eggs and hatchling phenotypes of the fence lizard Sceloporus undulatus. Our experimental manipulations allowed us to determine if the pattern and amplitude of biologically meaningful moisture fluctuations influence fitness-related traits of hatchlings. A release-recapture experiment in the field allowed us to explore post-hatching survival under natural conditions. In general, we detected minimal effects of moisture fluctuations during incubation on egg survival, initial hatchling phenotypes, and post-hatching survival. Initial growth rates of hatchlings, however, increased in treatments with fluctuating moisture conditions resulting in larger hatchlings after 4 weeks. These increased initial growth rates likely indicate slower yolk metabolism during embryogenesis in fluctuating treatments. Our results suggest that eggs of S. undulatus are extremely efficient at absorbing moisture from the surrounding environment and are resilient to short-term exposure to potentially lethal moisture conditions.