Fig. 1

Distribution of genetic diversity estimated from microsatellite data within and among populations of U. laevis in Switzerland and Europe. a Map showing the genetic structure and admixture of all U. laevis sampling localities (for K = 4). The assigned genetic groups are represented in different colors (red, yellow, orange, and green) according to b. The inset map shows the populations analyzed from Spain, Poland, and Hungary. Numbers in brackets indicate the population size. The outgroups are not represented on the map. b Summary of structure outputs, based on the whole dataset and k = 3–5, illustrating the power of our set of microsatellite markers to differentiate between Ulmus laevis and other Ulmus species (k = 3) and identify peculiar populations at European and regional scale. Populations showing peculiarities (k = 4–5). Each of the 371 U. laevis individuals (+ 39 outgroup individuals) is represented by a vertical line assigned to the clusters that are represented in different colors (red, yellow, orange, green, and blue). Populations are labeled with abbreviations as in Table 1 and grouped into countries (CH, FR, DE, ES, PL, and HU). Detailed outputs following the hierarchical approach described in the M&M section are presented in the dataset (Dermelj et al 2024, Figure S2)