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1 June 2003 Nest Temperature Is Not Related to Egg Size in a Turtle with Temperature-Dependent Sex Determination
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Abstract

A recent hypothesis posits that temperature-dependent sex determination (TSD) in reptiles may be maintained if females can assess thermal conditions and lay eggs accordingly to produce the sex benefiting most from maternal investment. Specifically, females should lay large eggs in environments likely to produce the sex benefiting most from larger egg size. This relationship has been demonstrated in diamondback terrapins. To evaluate the generality of this hypothesis, we examined two components of this hypothesis using painted turtles (Chrysemys picta), a reptile with TSD. Vegetation cover around nests at oviposition significantly and negatively influenced nest temperatures during embryonic development, particularly during the period of sexual differentiation. However, no relationship existed between egg mass and either nest temperatures or vegetation cover around nests at oviposition. Therefore, large eggs were not laid in specific thermal microenvironments as a mechanism to match egg size with offspring sex ratio. These results do not support a general relationship between thermally based nest-site choice and maternal investment (egg mass) in reptiles with TSD.

The American Society of Ichthyologists and Herpetologists
Carrie L. Morjan and Fredric J. Janzen "Nest Temperature Is Not Related to Egg Size in a Turtle with Temperature-Dependent Sex Determination," Copeia 2003(2), 366-372, (1 June 2003). https://doi.org/10.1643/0045-8511(2003)003[0366:NTINRT]2.0.CO;2
Received: 11 December 2001; Accepted: 30 November 2002; Published: 1 June 2003
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