Environmental sex determination in reptiles and amphibians in Strathcona

Warner and Shine used hormonal manipulations to produce males and females across a range of temperatures in a species with TSD. Retrieved April 16, — via ETI. This approach is significantly more rigorous than most differential display PCR studies because prior studies did not use biological replicates environmental sex determination in reptiles and amphibians in Strathcona.

While aromatase activity remains low for much of development in individuals that exhibit TSD, during the thermosensitive period, variations in temperature increase the activity of aromatase. It has been proposed [24] that temperature acts on genes coding for such steroidogenic enzymesand testing of homologous GSD pathways has provided a genic starting point.

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Hormones and temperature show signs of acting in the same pathway, in that less hormone is required to produce a sexual shift as the incubation conditions near the pivotal temperature. Other work centers on a theoretical model the Charnov — Bull model[33] [34] predicted that selection should favour TSD over chromosome -based systems when "the developmental environment differentially influences male versus female fitness"; [2] this theoretical model was empirically validated thirty years later [2] but the generality of this hypothesis in reptiles is questioned.

Functional Ecology. In this species, high incubation temperature during egg development reverses genotypic males ZZ into phenotypic females; so females can be ZZ or ZW, but males are always ZZ. New Jersey: Prentice Hall, Other environmental sex determination in reptiles and amphibians in Strathcona show disproportionately high female production at both high and low temperatures, with intermediate temperatures causing mostly male development.

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Optimum Health Vitamins. Berlin: Springer-Verlag, A diet rich in milk has been said to favour daughters, while other dietary changes which increase the acidity of the vagina have been said to favour Y sperm, and thus sons. Pieau, Claude.

Therefore, we also provide a prospectus on alternative approaches that promise to reveal new candidate genes and to elucidate functional interactions among these genes. Another group of cells differentiates into peritubular myoid cells, which envelop the testis cords to form seminiferous tubules [ Morrish and Sinclair, ].

Bands were cloned and sequenced as previously described [ Rhen et al. Testes develop when the inner medullary region of the genital ridge grows and differentiates [ Raynaud and Pieau, ; Wibbels et al. More examples of context-dependent sex determination will be studied in Chapter A widely held view is that temperature-dependent and genotypic sex determination are mutually exclusive, incompatible mechanisms—in other words, a reptile's sex is never under the influence of both sex chromosomes and environmental temperature.

Environmental sex determination in reptiles and amphibians in Strathcona

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