Dispersal across southern Iberian refugia? Integrating RAPDs, sequence data and morphometrics in Armeria (Plumbaginaceae)

Abstract

A southern Spanish massif (Tejeda/Almijara range, Málaga province, SE Spain) has been previously identified as a contact zone for genotypes of a rare taxon, Armeria villosa subsp. bernisii, and a frequent one, A. filicaulis, based on (1) the discovery of a species-independent geographically structured pattern of variation for nuclear ribosomal ITS sequence data and (2) the sharing of chloroplast haplotypes, which reveal horizontal transfer between the species. This study uses RAPD data, as a total DNA marker, and morphometrics, as potentially revealing hybridisation and introgression, to throw further light on the origin of the above mentioned contact zone. Individuals of the two taxa sampled from the range do not show a F1 hybrid profile for RAPD or for morphometrics. To integrate this results with the previously published sequence data (ITS and chloroplast spacer trnL-F) it is proposed that introgressive hybridisation has occurred in A. villosa subsp. bernisii, while for A. filicaulis the contact zone occurs at the intraspecific level. With the available data, the contact between individuals of Armeria with different genotypes in the two taxa may have involved westward migration from a biodiversity-rich massif like Sierra Nevada, and this may apply to other organisms although further data are needed to confirm it.