Temperature effects during early life stages of the alligator snapping turtle (Macrochelys temminckii)

Published source details Ligon D.B. & Lovern M.B. (2009) Temperature effects during early life stages of the alligator snapping turtle (Macrochelys temminckii). Chelonian Conservation and Biology, 8, 74-83.
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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: Tortoises, terrapins, side-necked & softshell turtles Action Link

Alter incubation temperatures to achieve optimal/desired sex ratio: Tortoises, terrapins, side-necked & softshell turtles

A replicated study in 2002–2004 in a laboratory in Oklahoma, USA (Ligon & Lovern 2009) found that incubating alligator snapping turtle Macrochelys temminckii eggs at higher temperatures resulted in strongly female-biased sex ratios, though the coldest and warmest temperatures resulted in very low hatching success. Warmer incubation temperatures produced almost all female hatchlings (28.5°C or 30.5°C resulting in 97% and 100% of female hatchlings), whereas incubating at 26.5°C resulted in 81% male hatchlings. The coldest (23.0 and 24.5°C) and warmest (31.0°C) incubation temperatures resulted in 0% hatching success, and hatching success was higher at 26.5°C (85%) compared to cooler (26.0°C: 33%) or warmer (30.5°C: 40%) temperatures. Eggs were obtained in 2002 (3 clutches of 15–37 eggs, 88 total) and 2004 (6 clutches of 17–42 eggs, 186 in total) and split evenly between six incubation temperatures in 2002 (23.0, 24.5, 26.0, 26.5, 28.5 and 31.0°C; 12–13 eggs/temperature) and three temperatures in 2004 (53 eggs at 26.5°C; 51 at 28.5°C; 47 eggs at 30.5°C). Eggs were incubated in damp vermiculite (1:1 ratio with water by mass). Hatching success was assessed and hatchlings were sexed 267–278 after hatching by observing gonads via a non-lethal surgical procedure.

(Summarised by: William Morgan)