Temperature-dependent sex determination in reptiles While the sex of most snakes and most lizards is determined by sex chromosomes at the time of fertilization, the sex of most turtles and all species of crocodilians is determined by the environment after fertilization.
One possible explanation that TSD is common in amniotes is phylogenetic inertia — Temperature dependent sex determination animals quarry in Prince George is the ancestral condition in this clade and is simply maintained in extant lineages because it is currently adaptively neutral or nearly so.
Integrative and Comparative Biology. Sunderland MA : Sinauer Associates ;
TSD is very common in reptiles, where the ambient temperature during sensitive periods of early development irreversibly determines whether an individual will be male or female. Bull, James. Read Now. Charnier, Madeline.
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. Estrogen can override temperature and induce ovarian differentiation even at masculinizing temperatures.
Physiological and Biochemical Zoology.
Sex Chromosomes and Sex-Linked Genes. The scope of the model for other reptiles, however, requires further research. Turtles of the World. Keywords: Sex determinationReptilesTurtlesHormones. Very near or at the pivotal temperature of sex determination, mixed sex ratios and more rarely intersex individuals.
The eggs are affected by the temperature at which they are incubated during the middle one-third of embryonic development. Turn recording back on. Two individuals are changing from male to female. Individuals with low levels of aromatase during the thermosensitive period will develop male characteristics.