Figure 1. Quantities of sex reversal (contradiction between genetic and phenotypic sex) under the influence of 17α-ethinylestradiol (EE2) in three deeply diverged anuran amphibians.

Percentages of genetic-male-to-phenotypic-female sex reversal in African clawed frogs (Xenopus laevis, red), European tree frogs (Hyla arborea, green), and European green toads (Bufo viridis, blue) exposed to three concentrations of EE2 and in control animals; pooled data from two replicate experiments for each treatment or control. Susceptibility differences in genetic-male-to-phenotypic-female sex reversal occurred at all concentrations: (*) significant differences between clawed frogs and tree frogs (p ≤ 0.010); (^x) significant differences between clawed frogs and green toads (p ≤ 0.001). Statistical analyses were conducted using cross-tabulation, Chi square and Fisher´s exact tests (α = 0.05).