Origin of the Woody Macaronesian Sempervivoideae and the Phylogenetic Position of the East African Species ofAeonium

Evolutionary relationships among the genera of Macaronesian Sempervivoideae,Aeonium, Aichryson, Greenovia, andMonanthes, were studied using sequence variation of the chloroplast DNAtrnL(UAA) ‐trnF(GAA) spacer and the nuclear ribosomal Internal Transcribed Spacer 2 (ITS2). Phylogenetic analysis indicates that the MoroccanSedumsect.Monanthoideais the sister taxon of the Macaronesian Sempervivoideae. In combination with the terminal position in the Macaronesian Sempervivoideae of the East AfricanA. leucoblepharum, which has formerly been assumed to be the sister taxon of the other species of Macaronesian Sempervivoideae (i.e.AichrysonandMonanthes), a recent remigration to Africa is suggested. Statistical support for the terminal position ofA. leucoblepharumusing only spacer sequences is without homoplasy but not high since only single mutations in both the chloroplast and nuclear sequence characterize the clade containingA. leucoblepharum. A. leucoblepharumand the Canarian species with a similar growth‐form share 50% of the RAPDs. Within a clade comprising woody species with yellow flowers and a herbaceous rosette, the highest genetic divergence, as determined with RAPDs, is found betweenA. simsiiand the woody Macaronesian and African species. The extremely close genetic ties among the woody and branched (sub)shrubs indicate that, when compared to the other species of the genus, the woody, AfricanAeoniumspecies are not the sister group of the Macaronesian Sempervivoideae and substantiate the view that an ancestor ofA. leucoblepharumrecently migrated from the Canary Islands to East Africa and Arabia through long distance dispersal, rather than being a relict of an AfricanAeoniumflora from the Tertiary.