Corticosterone plasma levels of embryo and hatchling broad-snouted caimans (Caiman latirostris) incubated at different temperatures

Published source details Parachú Marcó M.V., Piña C.I., Somoza G.M., Jahn G.A., Pietrobon E.O. & Iungman J.L. (2015) Corticosterone plasma levels of embryo and hatchling broad-snouted caimans (Caiman latirostris) incubated at different temperatures. South American Journal of Herpetology, 10, 50-57.
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This study is summarised as evidence for the following.

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	Alter incubation temperatures to achieve optimal/desired sex ratio: Crocodilians Action Link

Alter incubation temperatures to achieve optimal/desired sex ratio: Crocodilians

A replicated, randomized study in 2013 in laboratory conditions in Santa Fe province, Argentina (Parachú Marcó et al. 2015) found that altering the incubation temperature of broad-snouted caiman Caiman latirostris eggs did not affect hatching success, but that females were only produced below a temperature threshold. Hatching success was similar across all temperatures (26 of 30, 88% at 31°C; 25 of 29, 85% at 33°C; 23 of 29, 78% at 34°C). Incubation at 31°C produced all females (46 eggs), whereas incubation at 33°C (45 eggs) and 34°C (43 eggs) produced all males. In 2013, a total of 134 viable eggs were collected from four wild nests and clutches were split evenly between three incubation temperatures (31, 33 or 34°C) with two groups/temperature. Eggs were incubated in moist vermiculite at high humidity. Forty-six eggs were dissected during development, just after the thermosensitive period when sex is determined. Sex was assessed by histological methods (46 embryos and 14 hatchlings) or by visual examination four months after hatching (74 hatchlings).

(Summarised by: William Morgan)