Fig. 3

Marginal response and occurrence density curves of four highly contributing predictors common to both species. Response curves of the four predictors included among the six most contributing ones for both Lissotriton italicus and L. vulgaris meridionalis within the cross-validated BRT models built on the current bioclimatic conditions. Predicted suitability for L. italicus (triangles) and L. v. meridionalis (circles) in the occurrence localities within the sympatric area is shown on each plot, together with the respective occurrence density curves obtained through the Ecospat package. A map showing the values of the corresponding predictor within the portion of the Central Apennines including the sympatric area is also shown beside each plot