Descriptive distribution models for six amphibian species across Portugal. Descriptive distribution models for six amphibian species across Portugal. Models are derived with stepwise logistic regression analysis of the dependent variable 'presence-absence of the target species' against 13 independent ecological variables (details see text and Table 1). The estimated probability of occurrence (g) ranges from 0 (blue) to 1 (red). Composite colours represent intermediate probabilities as in the colour scale bar. Species are: a) Chioglossa lusitanica, b) Pleurodeles waltl, c) Triturus marmoratus, d) T. pygmaeus, e) Alytes cisternasii and f) A. obstetricans. Recorded presences over the 10 × 10 km UTM-grid are shown by black shadings, after Godinho et al. .