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

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.