Developmental plasticity in an unusual animal: the effects of incubation temperature on behavior in chameleons

Abstract

The thermal environment within a reptile nest can affect the phenotypic traits of hatchlings, and hence (potentially) their fitness. Research on this topic needs to measure phenotypic traits relevant to the species involved; and hence, studies on unusual species need to measure unusual traits. We investigated the effects of two incubation temperatures on the morphology and behaviour of hatchling veiled chameleons (Chamaeleo calyptratus). Colder-incubated eggs exhibited a longer incubation period, but produced larger faster-growing hatchlings. Incubation treatment also affected a chameleon’s activity level and its unique foraging tactics. Cold-incubated animals were more sedentary, caught prey faster, and extended their tongues farther to reach prey than did their warm-incubated counterparts. Thus, the fitness costs of low temperatures in the nest (slow development, and thus late hatching) may be offset by incubation-derived enhancements in hatchling growth rates and foraging abilities.