In some species, including most mammals and insects, sex is determined solely by chromosomes; in other species, sex is a matter of environmental conditions. All crocodilians, most turtlesmany fishand some lizards exhibit TSD. An alternative hypothesis of adaptive significance was proposed by Bulmer and Bull in  and supported by the work of Pen et al.
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It is quite possible that there are other species of reptiles with more complicated scenarios of temperature reversal of chromosomal sex. What causes a sea turtle to be born male or female? Integrative and Comparative Biology. Most turtles are subject to temperature-dependent sex determination.
Journal of Temperature dependent sex determination tortoise in Carnarvon. NCBI Bookshelf. Temperature-dependent aromatase activity is also seen in diamondback terrapins, and its inhibition masculinizes their gonads Jeyasuria et al.
Clear Turn Off Turn On. Spencer and Janzen found that hatchlings from mixed-sex nests were less energy efficient and grew less than their same-sex counterparts incubated in single-sex producing temperatures. Pieau, Claude. The pathways toward maleness and femaleness in reptiles are just being delineated.
Research shows that if a turtle's eggs incubate below Young individuals are always male.
Pieau, Claude. At temperatures in between, the broods will give rise to individuals of both sexes. Global Change Biology.