Do incubation-induced changes in a lizard's phenotype influence its vulnerability to predators?

Strong evidence affirms that incubation temperatures can influence the phenotype of hatchling reptiles, but few studies have examined the fitness consequences of such modifications. Vulnerability to predation is one plausible way that phenotypic shifts could affect an organism's fitness. We incubated the eggs of three sympatric lizard species at temperatures similar to the thermal extremes of natural nests, and measured several traits that are likely to influence a hatchling's susceptibility to a natural (snake) predator. We also examined the lizards' actual vulnerability to snake predators in direct encounters in the laboratory. Our results show that incubation temperature can affect an individual's date of hatching, morphology, locomotor performance, chemosensory responses to snake scent, and ability to avoid a snake predator during staged laboratory encounters. Incubation temperature did not modify the hatchling's 'attractiveness' to snakes (as measured via chemical cues) or its antipredator tactics (propensity to escape predation through fleeing or caudal autotomy). The magnitude and direction of incubation-induced phenotypic shifts varied among the three species (even those with similar life histories, thermoregulatory preferences, and microhabitat requirements), and depended on body temperatures and hatchling age. We conclude that incubation-induced modifications to a lizard's phenotype affect a suite of traits that are likely to influence its vulnerability, and also its actual ability to escape from a predator. This result suggests that incubation regimes can influence organismal fitness via their effects on predator-prey interactions.