Geographic distribution and cpDNA tree of P. marginata and relatives. A) Geographic distribution of sampled populations of P. marginata, P. allionii, P. latifolia and P. hirsuta in the Western Alps and Northern Apennines; B) Bayesian 50% majority-rule consensus tree of Primula sect. Auricula accessions; Posterior Probability (PP) values are indicated. P. marginata hexaploids = green squares; P. marginata dodecaploids = red squares; P. allionii = blue triangles; P. latifolia = yellow circles; P. hirsuta = pink diamonds. Ploidy levels according to flow cytometry data of the present study (Table 1). Population codes as in Table 4 and Additional file 1.