Fig. 1
Schematic distribution of the Zootoca vivipara clades in Eurasia and climatic predictions derived from the three hypothesis explaining the evolution of viviparity. Dots on the map refer to populations used to disentangle among the hypotheses and dot colour to the genetic clade affiliation; green: clade A, blue: clade B, purple: clade C, orange: clade D, pink: clade E, and yellow: clade F. Distributions of viviparous clades are coloured in light green and those of oviparous lizards are in dark green. Letters on the geographic map refer to genetic clades [29]. On the right of the map, climatic predictions (abbreviated as ‘P’), derived from three hypothesis explaining the evolution and maintenance of viviparity. Predicted range differences of optimal incubation temperature and differences in average incubation temperature (black ‘-‘within range) for viviparous (light green) and oviparous (dark green) lizards are shown for each hypotheses. \( \overline{X} \) corresponds to average incubation temperature, σ2 to the variance in incubation temperature, ‘>’ indicates that values are bigger in oviparous clades, ‘=’ indicates that there exists no differences among parity modes, and ‘<’ indicates bigger values in viviparous clades. The predictions for each of the three hypotheses are abbreviated using lowercase numbers. For simplicity, only the predictions related to temperature are shown, while the general predictions are stated in the article’s text