THE INFLUENCE OF NATURAL INCUBATION ENVIRONMENTS ON THE PHENOTYPIC TRAITS OF HATCHLING LIZARDS

Laboratory studies have shown that incubation environments can affect morphological and behavioral phenotypes of hatchling lizards, but the relevance of this result to natural populations remains unclear. We monitored thermal regimes during the incubation period in 19 natural nests of scincid lizards (Bassiana duperreyi) in montane southeastern Australia, and experimentally translocated eggs among nests to remove the confounding of “nest of origin” (including genetic) factors with incubation conditions. We removed the eggs from the field shortly before hatching, and assessed the hatchlings’ phenotypes (body size, shape, locomotor performance). Most of the effects seen after laboratory incubation were also seen after incubation in natural nests. Hatchling phenotypes were affected by incubation conditions as well as by “nest of origin” factors and an interaction between the two. Both the mean and the variance of incubation temperatures affected hatchling phenotypes, with male and female hatchlings differing in their norms of reaction. We found no evidence that a female’s choice of nest site depends on the specific norms of reaction of her own offspring. Overall, incubation temperatures induced approximately half as much variance in hatchling phenotypes as did “nest-of-origin” effects. We conclude that incubation-induced phenotypic plasticity in hatchling reptiles may be important in the natural environment, as well as in the laboratory.