Effect of Prenatal Exposure to Corticosterone on Broad-Snouted Caiman (Caiman latirostris) Hatchlings

Living organisms face stressful situations and use endocrine mechanisms, such as glucocorticoid production, to maintain homeostasis. Although glucocorticoids are essential for basal function, their secretion increases when organisms face stressful situations. In species with temperature-dependent sex determination (TSD), like Caiman latirostris, an increase in these hormones could also alter the sex ratio. In this study, we applied a dose of exogenous corticosterone (70 ng/egg) at developmental stage 20 to assess its effects on sex determination, incubation period (IP), and morphometric traits -including snout-vent length, total length, and body mass- in embryos and hatchlings. Eggs (n = 184) were incubated at 32°C, a temperature that typically produces both sexes. Corticosterone treatment significantly reduced the IP (CORT: 74  ±  2 days; CONTROL: 78  ±  2; z = -9.91, p < 0.01), without affecting hatching success. Morphometric traits did not differ significantly between treatments in either embryos or hatchlings (all p > 0.05). However, a marked shift in sex ratio was observed: while a 30% male to 70% female ratio was expected, corticosterone treatment reversed this pattern, resulting in 75% males and 25% females (χ² = 6.125, p = 0.013). These results indicate that corticosterone can induce male-biased sex differentiation and accelerate hatching without compromising morphological development or hatchling viability. While this mechanism could confer a advantage at the individual level by allowing earlier hatching, it is crucial to investigate whether it carries long-term costs, both in the growth and survival of the offspring and in population dynamics due to the altered sex ratio.