Phylogenetic relationships
The phylogenetic relationships among C. gr. laevigataspecies established by the c90m6 matrix of RAD-seq SNPs (Fig. 2, Fig. S1) are congruent with the previous studies but resolved the intermingled relationships that have been previously obtained forC. laevigata-C. binervis (Escudero et al., 2009; Escudero & Luceño, 2010). Carex paulo-vargasii and C. camposii were retrieved as subsequent sisters to the remaining species. Carex laevigata constitutes a monophyletic species, while C. binerviswas retrieved as polyphyletic, with two distinct lineages, an early-diverging one (sister to all C. gr. laevigata ) that is composed of populations from France and the British Islands (Eurosiberian part of the species range), and an Iberian (Mediterranean part of the species range) C. binervis lineage that was retrieved as sister to C. laevigata . In turn, C. laevigata was composed of a main clade restricted to the southern Iberian Peninsula (2n = 72–76), sister to another main clade with a wider distribution, spanning the species range and chromosome number variability (2n = 69–84).