Comment on: Carter AW, Paitz RT, Bowden RM. 2019. The Devil is in the Details: Identifying Aspects of Temperature Variation that Underlie Sex Determination in Species with TSD. Integrative and Comparative Biology 59:1081-8

We read with interest the article by Carter, Paitz, and Bowden entitled “The Devil is in the Details: Identifying Aspects of Temperature Variation that Underlie Sex Determination in Species with TSD” (2019; Integr Comp Biol 59:1081–8). In their article, Carter et al. (2019) studied the sex ratios produced by the eggs of Trachemys scripta, a freshwater turtle with TSD, incubated in vitro under various fluctuating temperature regimes. They then explored the explanatory values of metrics for the observed sex ratios, grouping their observations with those described by Carter et al. (2018). Their main result and conclusion were that a new metric—the daily duration with constant-temperature equivalent (DDC)—performed better than the constant temperature equivalent proposed by Georges et al. (1994) (hereafter, Georges’ CTE). The DDC is the number of days spent at a CTE superior to the pivotal temperature (which gives both sexes under constant incubation temperatures, Tpiv) during the temperature-sensitive period (TSP), which is the period of development when sex is irreversibly determined. We question the general value of this result.