If the snail is attached to a female, it will become male. Warner and Shine used hormonal manipulations to produce males and females across a range of temperatures in a species with TSD. One of the best-studied reptiles is the European pond turtle, Emys obicularis.
The adaptive significance of TSD is currently not well understood. They concluded that this differentiation in climate causes divergent selection on regulatory elements in the sex-determining network allowing for the emergence of sex chromosomes in the highlands.
One possible explanation that TSD is common in amniotes is phylogenetic inertia — TSD is the ancestral condition in this clade and is simply maintained in extant lineages because it is currently adaptively neutral or nearly so.
Evolution; International Journal of Organic Evolution. However, there is evidence that during climactic extremes, changes in the sex determining mechanism itself to GSD are selected for, particularly in the highly-mutable turtles.
The highlands are colder with a higher magnitude of annual temperature fluctuation and a shorter activity season, delaying maturity, thus GSD is favored so sex ratios are not skewed. However, there is evidence that during climactic extremes, changes in the sex determining mechanism itself to GSD are selected for, particularly in the highly-mutable turtles.
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. Sinauer Associates: Massachusetts. Help Community portal Recent changes Upload file.
The extent of the TSP varies a little among species,  and development within the oviducts must be taken into account in species where the embryo is at a relatively late stage of development on egg laying e. Environmental Sex Determination - Developmental Biology.
This evolutionary model, called the Charnov-Bull model, outlines the conditions under which the evolution of environmental sex determination occurs, and scientists later applied it to vertebrates with TSD. Archived from the original on If the snail is attached to a female, it will become male.