Phylogeographic patterns in Hypochaeris section Hypochaeris (Asteraceae, Lactuceae) of the western Mediterranean

Aim To analyse phylogeographic patterns in the four species of Hypochaeris sect. Hypochaeris, evaluating possible areas of origin and the microevolutionary processes that have shaped their morphology, genetics and distribution. Location Western Mediterranean area. Methods We applied amplified fragment length polymorphism (AFLP) markers to a total of 494 individuals belonging to 82 populations of Hypochaeris arachnoidea, H. glabra, H. radicata and H. salzmanniana to determine population structure. Results Populations with the largest proportion of private and rare AFLP fragments were found in Morocco. This region was consequently inferred to be the ancestral area for H. arachnoidea, H. glabra, H. radicata and H. salzmanniana. The Guadalquivir River (southern Spain) was inferred to be an effective dispersal barrier for H. glabra and H. radicata. The Strait of Gibraltar was inferred to be a somewhat weaker barrier than the Guadalquivir River for H. radicata and a much weaker barrier for H. glabra. The main barrier for H. salzmanniana coincides with the extension of the Rif Mountains to the Atlantic coast in Morocco, and the Strait of Gibraltar is a much weaker barrier for this species. Hypochaeris arachnoidea appears to have originated in the Atlas Mountains. Main conclusions The highest levels of genetic variation in La Mamora forest (H. glabra and H. salzmanniana) or the adjacent central Middle Atlas (H. arachnoidea and H. radicata) in Morocco suggest that these areas were a centre of origin of Hypochaeris sect. Hypochaeris. All three potential barriers - the Guadalquivir River, the Strait of Gibraltar, and the Rif Mountains - have been important in shaping genetic diversity in species of section Hypochaeris.