GENETIC-STRUCTURE OF CONTINENTAL AND ISLAND POPULATIONS OF THE MEDITERRANEAN ENDEMIC CYCLAMEN BALEARICUM (PRIMULACEAE)

Cyclamen balearicum is a self-compatible perennial herb endemic to the western Mediterranean Basin. This species occurs in five geographical ly isolated terrestrial islands in southern France and on four Baleari c islands. Tn this study, we compare genetic Variability and different iation within and among 11 terrestrial island populations and 17 true island populations. Of nine readable enzyme loci, five were polymorphi c in both terrestrial and true islands. F statistics showed a signific ant heterozygote deficiency in all populations, probably due to high l evels of autonomous selfing, restricted gene flow, and subsequent gene tic drift. Genetic diversity was higher in terrestrial islands than on the Balearic islands, suggesting that the Balearic islands were colon ized when they were in contact with the continent. Population differen tiation was greater among terrestrial islands (F-st = 0.417 and G(st) = 0.344) than among true islands (F-st = 0.112 and G(st) = 0.093). Fur thermore, differentiation among populations on the Basses Cevennes ter restrial island was greater (F-st = 0.254) than among populations on t he true island of Mallorca (F-st = 0.163). The greater genetic differe ntiation among terrestrial islands could have been caused by genetic b ottlenecks associated with changes in climate and human land use that may have reduced population sizes more severely in terrestrial islands in southern France than on the Balearic islands.