Effect of temperature fluctuation during incubation on sex determination in Caiman latirostris

BELLA, M.; SIMONCINI, M.; LARRIERA, A.; PIÑA, C. I.; LEIVA, P. M. L.

Chetumal

Congreso; XXVI Working Meeting Crocodiles Specialist Group - UICN; 2022

Crocodiles Specialist Group - UICN

Caiman latirostris presents temperature sex determination (TSD). Most of the studies onTSD have been done under constant incubation temperature, but such situationdoes not occur in nature. In this work we evaluate the sex ratio of nestsincubated under fluctuating thermal daily cycles. We also evaluated if cyclesaffect hatching success, incubation period, and hatchling size. We set up fourtreatments, (a) 15 hours at 31°C and 9 hours at 33°C; (b) 9 hours at 31°C and15 hours at 33°C, and 24 hours constant (c) 31°C and (d) 33°C. Sex ratio intreatment (a) was 77% females, (b) 23% females, and as expected (c) 100%females and (d) 100% males. Hatching success and morphological parameters werenot affected by cycling incubation temperature; on the other hand incubationperiod was shorter as incubation time at 33°C was longer. Analysis of femalesindicated that as incubation time at 33°C increased, females were smaller; norelationship was found for males, suggesting a possible stress effect only forfemales. Our results indicate that staying up to 40% of the day at maleinducing temperature compared to constant incubation at 31°C reduced femaleproduction from 100% to 77%, but staying about 60% of the time at male inducingtemperatures reduces female production to 23%.