Figure 1. A in A two-species distribution model for parapatric newts, with inferences on their history of spatial replacement

Figure 1. A, the outer range borders of the crested newt, Triturus cristatus (c; southern border shown by continuous line) and the marbled newt, Triturus marmoratus (m; northern and eastern border shown by dashed line) in continental France, after Castanet & Guyetant (1989) and Lescure & De Massary (2012). Departments mentioned in the text are as follows: DS, Deux-Sevres; M, Mayenne; V, Vienne. The Lower Rhône T. cristatus population is indicated by LR. The base map was downloaded from MapsLand (https://www.mapsland.com), under a Creative Commons Attribution-ShareAlike 3.0 Licence. B, the area of T. cristatus–T. marmoratus range overlap in Mercator projection, with the generalized species border as inferred from a two-species distribution model (see Fig. 2). The open circles represent documented species occurrences that strongly contradict the model, for T. cristatus (probability of occurrence, Pc ≤ 0.2, in red) and T. marmoratus (Pc ≥ 0.8, in blue). Large symbols represent multiple observations at close range. The drawings of animals, with T. cristatus at the top and T. marmoratus at the bottom, are by Bas Blankevoort, Naturalis Biodiversity Center.