Influence of temperature variation on incubation period, hatching success, sex ratio, and phenotypes in Caiman latirostris

SIMONCINI, MELINA S.; LEIVA, PAMELA M.L.; PIÑA, CARLOS I.; CRUZ, FELIX B.

Journal of Experimental Zoology Part A: Ecological and Integrative Physiology

wileyonlinelibrary.com

Año: 2019 vol. 331 p. 299 - 307

Temperature is crucial for reptiles, also during embryonic development, particularly forspecies with temperature‐dependent sex determination. Under natural conditions, Broadsnoutedcaiman (Caiman latirostris) eggs are influenced by thermal changes in the interior ofthe nest related to the external environmental temperature. As nests are subject tovariations in temperature and most lab studies on crocodilian incubation have been carriedout at constant temperatures, we were interested in determining how temperaturefluctuations may affect the development of caiman embryos. We investigated the effectsof incubation at constant temperatures (31°C, 32°C, and 33°C) and fluctuatingtemperatures (31 ± 2, 32 ± 1, and 32 ± 2°C) on the following aspects: incubation periodduration, hatching success, sex ratio, total length, and body mass of C. latirostris hatchlings.Eggs incubated at 31°C produced 100% females, those at 32°C produced 71.6% females(however, the sex ratio was nest related), and at 33°C produced 100% males. We found amasculinizing effect when incubation was at 31 ± 2°C compared with a constant 31°C; andtemperature fluctuations at 32°C (32±1 and 32±2°C) had a negative effect on hatchlingssize and mass, and hatching success compared with constant incubation temperatures of32°C and 33°C. Finally, the effect of temperature variation during the incubation period onsex ratio, hatching success, and phenotype depends on the mean temperature, as thefluctuation around 31°C affected the sex ratios and incubation period, and the fluctuationaround 32°C affected hatchling success and size.