Charruau, P., D. A. Martínez, G. Cantón & F. R. Méndez de la Cruz

Additional details on temperature-dependent sex determination in Crocodylus acutus. pp. 304-308.

Abstract. Some concern exists about how the global increase of environmental temperatures might modify crocodile nest temperatures and affect the physiological and morphological characteristics of hatchlings and as a consequence, population dynamics. Therefore, American crocodile (Crocodylus acutus) eggs were incubated at a wide range of constant temperatures to study the effects on hatchling sex, embryo viability, and duration of incubation. Our findings suggest that an increase in incubation temperature could lead to shorter incubation periods and improved hatching synchronization, which would enhance embryo and hatchling survival. However, high incubation temperatures (> 34.0°C) would also cause high mortality of embryos. Incubation temperatures keeping C. acutus embryos viable are likely to range from 28.5 to 34.5°C, with an optimum temperature range between 31.7 and 33.5°C. A temperature-dependent sex determination type II pattern is confirmed for C. acutus, with the production of a majority of females at low (≤ 31.0°C) and high (> 33.6°C) temperatures and the production of 100% of males at intermediate temperatures (from 31.7 to 32.8°C). Pivotal temperatures (50% of each sex produced) are to be expected between 31.1 and 33.6°C.
Key words. American crocodile; artificial incubation; survival rate; incubation temperature; hatching synchronicity; incubation period; Yucatán Peninsula.