Probability of reaching Gosner stage 31 or higher (Gosner 1960) for tadpoles of native rural (Durban Rural), native urban (Durban Urban), and non-native urban (Cape Town) origin at an age of 40/41 days as predicted from our generalised linear mixed effect model. Presented are boxplots. The boxes denote the interquartile ranges (IQR), the bars inside the boxes correspond with the predicted medians from the models. The whiskers extend to 1.5 × IQR. Asterisks denote significant differences as determined by post-hoc multiple comparisons.