Temperature-dependent sex determination
نویسنده
چکیده
Reptiles posses two main mechanisms of sex determination. In some species the sex of the individual is determined at conception by sex factors contained in sex chromosomes (termed genotypic sex determination or GSD). However, in other species sex is determined after conception by the environmental temperature during incubation and cannot be predicted by zygotic genotype (Bull, 1983; Valenzuela et al., 2003). This peculiar mechanism, termed ‘temperature-dependent sex determination’ (TSD) is one of several existing types of environmental sex determination among animals but the only one so far described reliably for reptiles. TSD has persisted for millions of years although it is still not known whether TSD is ancestral to reptiles. Sex ratios under TSD can be biased and the prevalence of this mechanism over time is somewhat surprising given the drastic environmental changes in temperatures that the earth has undergone. In this chapter how the incubation environment affects sex determination in reptiles from a thermal and molecular standpoint is reviewed, and the evolution of TSD is briefly considered.
منابع مشابه
A Systems Level Analysis of Temperature - Dependent Sex Determination in the Red - Eared
A Systems Level Analysis of Temperature-Dependent Sex Determination in the Red-Eared Slider Turtle Trachemys Scripta Elegans
متن کاملClimate change and temperature-dependent sex determination in reptiles.
Despite increasing concern over the possible impact of global temperature change, there is little empirical evidence of direct temperature effects on biotic interactions in natural systems. Clear assessment of the ecological and evolutionary impact of changing climatic temperature requires a natural system in which populations exhibit a direct unambiguous fitness response to thermal fluctuation...
متن کاملMutual information reveals variation in temperature-dependent sex determination in response to environmental fluctuation, lifespan and selection.
Quantifying the degree to which sex determination depends on the environment can yield insight into the evolution, ecological dynamics, and functional aspects of sex determination. In temperature-dependent sex determination (TSD), theory often predicts a complete dependence of sex on temperature, with a switch-like reaction norm. However, empirical data suggest more shallow relationships betwee...
متن کاملAnalyzing the coordinated gene network underlying temperature-dependent sex determination in reptiles.
Although gonadogenesis has been extensively studied in vertebrates with genetic sex determination, investigations at the molecular level in nontraditional model organisms with temperature-dependent sex determination are relatively new areas of research. Results show that while the key players of the molecular network underlying gonad development appear to be retained, their functions range from...
متن کاملTemperature-Dependent Sex Determination in Reptiles
The sex of a reptile [6] embryo partly results from the production of sex hormones [7] during development, and one such process to produce those hormones [8] depends on temperature of the embryo's environment. The production of sex hormones [7] can result solely from genetics or from genetics in combination with the influence of environmental factors. In genotypic sex determination [9], also ca...
متن کاملTemperature-dependent sex determination in the red-eared slider turtle, Trachemys scripta.
Temperature-dependent sex determination (TSD) in the red-eared slider turtle, Trachemys scripta, has been the subject of a variety of past studies. Incubation temperature appears to affect sex determination in a dose-dependent fashion. This suggests that temperature could be affecting a dosage-sensitive element in the sex-determination cascade. Sex determination in T. scripta is sensitive to es...
متن کامل