Embryo Project Encyclopedia
The Embryo Project Encyclopedia (https://embryo.asu.edu) is an open-access digital encyclopedia devoted to recording and contextualizing the science of embryos, development, and reproduction. The collection of documents, images, and multimedia housed here serves as the Encyclopedia's permanent archive.
Jane Maienschein, ASU University Professor, Regents Professor, and Director of the Biology and Society Program, started the Embryo Project Encyclopedia in 2007 with support from the National Science Foundation.
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- All Subjects: Sex Differentiation
- Creators: Racine, Valerie
In 2008 researchers Daniel Warner and Richard Shine tested the Charnov-Bull model by conducting experiments on the Jacky dragon (Amphibolurus muricatus), in Australia. Their results showed that temperature-dependent sex determination(TSD) evolved in this species as an adaptation to fluctuating environmental temperatures. The Charnov-Bull model, proposed by Eric Charnov and James Bull in 1977, described the evolution of TSD, although the model was, for many years, untested. Many reptiles and some fish exhibit non-genetic sex determination, in which an embryos' environment can influence the sex of the adult organism. Environmental conditions such as humidity or population density can alter sex in some organisms, and a widespread form of non-genetic sex determination is temperature-dependent sex determination. TSD reveals how embryonic development can contribute to the evolution of physiological processes. Researchers have documented TSD in a wide range of species, and they continue to investigate how such a sex determining system has evolved.