Effects of Temperature on Sex Determination in Embryos of the Snapping Turtle, Chelydra serpentina

Abstract

Temperature-dependent sex determination was studied in eggs of snapping turtles in both the laboratory and field. It has previously been shown that warm (30°C) and cold (20°C) temperatures cause female development, and intermediate temperatures (22°C-28°C) cause male development. Here it was found in the laboratory that exposure to at least 4 h/day at 30°C ensured female development, but shorter exposures resulted in some males (if a male-determining temperature was used over the remaining interval). In the field, eggs at the top of nests were significantly warmer (above 30°C) than those at the bottom (below 30°C), resulting in all females from top eggs, and often, all males from bottom eggs.