The influence of the pre- and post-natal environment on Tokay gecko (Gekko gecko, Squamata, Gekkonidae) development in captivity

Birgit Szabo

In captivity, reptiles often experience unnatural incubation and rearing conditions due to limited nest site choices, which can negatively impact individual development and welfare. Incubation temperature and humidity are especially critical for reptile development, influencing factors such as sex, growth, and morphology. However, the conditions experienced after hatching, such as social housing, are far less often considered. Here, I studied the effects of both the incubation environment (temperature and humidity) and social rearing compared to isolation rearing on the development of captive bred tokay geckos (Gekko gecko). I find that incubation temperature but not humidity are associated with phenotypic sex, hatchling size and incubation duration. Furthermore, females selected nest sites with higher temperature and lower humidity. After hatching, rearing group size did not affect snout vent length, growth or body condition. My findings indicate an association between incubation temperature and phenotypic sex despite the presence of sex chromosomes in this species. Therefore, care should be taken when raising tokay geckos in captivity to provide nest site options and ensure optimal development of all offspring.