Phylogeography and seed dispersal in islands

Rumex bucephalophorus subsp. canariensis (Polygonaceae) is an endemic taxon to Macaronesia with diaspore polymorphism. Talavera et al. use AFLP analysis to study 260 plants from 22 populations across the Madeiran and Canary archipelagos and find a geographical pattern of genetic diversity that is higher in the older eastern islands than in the younger western ones. In the eastern Canary islands plants produce exclusively long-dispersible diaspores, whereas in the western Canary islands and the Madeiran archipelago plants produce exclusively short-dispersible diaspores. They hypthesise a Morroccan origin for the species and conclude that during the colonization process the type of dispersible diaspore changed so that dispersability decreased in populations of the westernmost islands.