New evidence characterizing temperature-dependent sex determination in broad-snouted caiman, Caiman latirostris

Published source details Parachú Marcó M.V., Leiva P., Iungman J.L., Simoncini M.S. & Piña C.I. (2017) New evidence characterizing temperature-dependent sex determination in broad-snouted caiman, Caiman latirostris. Herpetological Conservation and Biology, 12, 78-84.
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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 (year not provided) in Santa Fe province, Argentina (Parachú Marcó et al. 2017) found that when altering incubation temperatures of broad-snouted caiman Caiman latirostris eggs, lower temperatures resulted in a higher number of female hatchlings compared to higher temperatures. At 31°C, all hatchlings were female, and at 33°C and 34°C all hatchlings were male (number of eggs/treatment not provided). At 32°C an average of 72% of hatchlings were female, but this varied from 17–100% depending on the nest of origin. Hatching success varied from 78–91% and was not affected by incubation temperature. A total of 172 eggs that were judged to be viable (by presence of opaque banding on egg) were collected from nine wild nests. Eggs were incubated at 32 or 33°C in the first year, and 31, 33 or 34°C in the second year. In both years, there were two groups/temperature, and eggs were split evenly between groups (number/treatment not provided). A total of 141 hatchlings were kept in captivity for four months, after which point sex was determined using histological methods (100 individuals) or by a visual examination (24 individuals).

(Summarised by: William Morgan)