Influence of temperature variations on the sexual proportion in Caiman latirotris

LEIVA, P.; SIMONCINI, M.; IUNGMAN, J.; PIÑA, C. I.

Lake Charles

Congreso; XXIII Working Meeting Crocodiles Specialist Group - UICN; 2014

Crocodile Specialist Group (UICN)

Caiman latirostris is an ectotherm animal that inhabits temperate zones, showing a marked seasonality on its activity. This species exhibits temperature sex determination, in which only males are produced at constant temperatures of 33°C , only females are produced at 29 and 31°C; and 34.5°C produces both sexes. Most studies of sex determination in crocodilians have been conducted under constant temperature conditions. Furthermore, the thermal influence on the sex ratio is poorly documented on wild. We study the sexual proportion produced in eggs of C. latirostris incubated at 32°C and exposed to constant thermal cycles approximately 32±1°C and 32±2°C during development. The design also allowed us to evaluate the effect of the variations of temperature on incubation period, hatching success and hatchling size. We located and collected five nests in study area of Proyecto Yacaré (Santa Fe province), which were incubated at different thermal treatments. Our results indicated that the variation in incubation temperature affects the sexual proportion of C. latirostris, owever each nest responded differently to heat treatment. The temperature variation treatments affected negatively the hatching success and size and weight of hatchlings, compared to the constant treatments, but incubation period was not affected.