2.1 Study species
Primula vulgaris (primrose) is an ancestrally heterostylous, diploid (2n=22) perennial, rosette-forming plant blooming from February to April. Distylous populations of P. vulgaris occur across Eurasia, including in Turkey, most of Western Europe, larger Mediterranean Islands, and all British Isles (Jacquemyn et al., 2009). In contrast, populations with varying frequencies of homostyles have been discovered only in Somerset and Chiltern Hills, England (Crosby, 1940, 1949), and one population in the Netherlands (Barmentlo et al. , 2017). Habitat fragmentation due to intensive pastoral and agricultural activities in these areas were suggested as the potential selective pressure favoring the shift to self-fertilizing homostyles in these populations (Mora-Carrera et al., 2021).