Maternal influences on early development: preferred temperature prior to oviposition hastens embryogenesis and enhances offspring traits in the Children's python, Antaresia childreni.

Embryonic life is particularly sensitive to its surroundings, and the developmental environment can have long-lasting effects on offspring. In oviparous species, the impacts of the developmental environment on offspring traits are mostly examined during development within the egg. However, as more than 25% of the development of squamate reptiles can occur prior to oviposition, we explored the effect of thermal conditions on development prior to oviposition in an oviparous snake species, the Children's python (Antaresia childreni). We housed gravid female pythons under three thermal cycles: an optimal regime that reflected maternal preference in a non-constrained environment (constant preferred body temperature of gravid females, T-set=31.5 degrees C) and two mildly suboptimal regimes that shared the same mean temperature of 27.7 degrees C, but differed in the duration at T-set. In one of the constraining regimes, females had access to T-set for 4. h daily whereas in the other regime, females never reached T-set (maximal temperature of 29.0 degrees C). Thermal treatments were maintained throughout gravidity in all three groups, but, after oviposition, all eggs were incubated at T-set until hatching. Compared with the optimal regime, the two suboptimal regimes had a longer duration of gravidity, which resulted in delayed hatching. Between the two suboptimal regimes, gravidity was significantly shorter in the treatment that included time at T-set. Furthermore, suboptimal regimes influenced offspring traits at hatching, including body morphology, antipredator behavior, strength and metabolism. However, partial access to maternal T-set significantly enhanced several offspring traits, including performance. Our results demonstrate the importance of time at T-set on early development and suggest an adaptive significance of maternal thermoregulation prior to oviposition.