Body Temperature, Thermoregulation And Thermal Dependence Of Egg Incubation And Food Use Of Five-paced Pit-viper, Deinagkistrodon Acutus (Viperidae)

The five-paced pit-viper (Deinagkistrodon acutus) is a large sized and highly venomous snake, ranging from the southern provinces of China (including Taiwan) to northern Vietnam. Snakes collected during 2004?2005 from Lishui, Zhejiang, to study (1) the effects of temperature on egg incubation and hatchling phenotypes; (2) the effects of food type, temperature and feeding frequency on food use and specific dynamic action; and (3) temporal variation in body temperature and thermoregulation of snakes both in an enclosure and in the laboratory.1. The effects of temperature on egg incubation and hatchling phenotypes.A total of 164 D. acutus eggs were incubated at five constant temperatures. Embryonic mortality increased dramatically at 30°C, and none of eggs incubated at 32°C hatched. Within the range from 24?30°C, temperature affected incubation length and most hatchling traits examined. The mean incubation length at 24, 26, 28 and 30°C was 36.4, 28.7, 21.8 and 15.7 days, respectively. Embryos developing at higher temperatures (28°C and 30°C) consumed more energy but produced less developed (and hence smaller) hatchlings, which characteristically had larger residual yolks but smaller carcasses. A principal component analysis resolved two components (with eigenvalues≥1) from ten size (initial egg mass)-free hatchling variables, accounting for 79.3% of variation in the original data. The first component (43.8% variance explained) had high positive loading for size-free values of dry mass, lipid mass, energy contents and ash mass of hatchlings, and the second component (35.5% variance explained) had high positive loading for size-free values of SVL, carcass dry mass and fatbody dry mass. Hatchlings from different incubation temperatures did not differ in scores on the first axis of the principal component analysis, whereas...