Edited by the world's foremost authorities on the subject, with essays by leading scholars in the field, this work shows how the sex of reptiles and many fish is determined not by the chromosomes they inherit but by the temperature at which incubation takes place.

The influence of varying egg geographic origin on resulting offspring sex ratios was also analyzed. Both field and laboratory-incubated eggs required approximately 150 degree-hours to produce at least 50% female offspring. Those eggs originating from more southern locations required fewer degree hours to produce a given percentage of female turtles. In other words, more female offspring from lower latitudes were produced within a particular temperature treatment than resulted from more northern latitudes.

Reptiles are a fascinating group for the study of sexual development because they exhibit a wide range of sex-determining mechanisms, from strict genetic sex determination (GSD) to strict thermal sex determination (TSD) and intermediate systems of GSD that are to various degrees overridden by environmental effects . This thematic issue presents the latest data on different aspects of sex determination in reptiles. Following an evolutionary perspective on why reptiles might be predisposed to evolve TSD, the papers in this issue explore in detail the different genetic and molecular mechanisms of sex determination and differentiation. They consider recent findings such as the discovery of new genes differentially expressed at male and female sex-determining temperatures, a new model of the role of aromatase, and the contribution of heat-shock proteins to TSD in the American alligator. Further studies examine the role played by sex allocation, the advantage of viviparity, and the effects of anthropogenic climate change on the sex ratio in TSD reptile populations. Providing a valuable overview for both students and researchers, this publication is essential reading for developmental and reproductive biologists, herpetologists, comparative endocrinologists, evolutionary biologists and geneticists.