Their results suggest that the temperatures an organism experiences during development significantly affect its reproductive success. Peters and four anonymous referees made helpful comments on the manuscript. For example, there is an Australian skink lizard that is genotypically governed by X and Y sex chromosomes.
Nature has provided many variations on her masterpiece. Spencer and Janzen found further support for the Charnov-Bull model by incubating painted turtles Chrysemys picta at different temperatures and measuring various characteristics indicative of fitness.
External link. In these reptiles, the temperature of the eggs during a certain period of development is the deciding factor in determining sex, and small changes in temperature can cause dramatic changes in the sex ratio Bull Very near or at the pivotal temperature of sex determination, mixed sex ratios and more rarely intersex individuals.
Endler, A. Scientific Data.
Here, we use the term sex to refer to the type of gonad that forms. Boa and Python families are now known to probably have an XY sex-determination system. Maternally derived yolk hormones vary in follicles of the painted turtle, Chrysemys picta.
Isolation of chicken homolog of the FOXL2 gene and comparison of its expression patterns with those of aromatase during ovarian development. Steroid hormone-induced male sex determination in an amniotic vertebrate.
To limit potential seasonal effects, we restricted egg collection to October and November in each year. Sunderland MA : Sinauer Associates; The pathways toward maleness and femaleness in reptiles are just being delineated. The warming of the habitats of species exhibiting TSD are beginning to affect their behavior and may soon start affecting their physiology.