Variation in the population genetic structure of two Cyclamen species on the island of Corsica

Cyclamen repandum and C. hederifolium occur in sympatry in many sites across their distributions but flower at different times. A previous controlled pollination experiment on plants of the two species collected on the island of Corsica showed no evidence of inbreeding depression over all measured life cycle stages in C. repandum, whereas C. hederifolium showed inbreeding depression (multiplicative delta = 0.49) on fruit maturation and seed production. This suggests that C. repandum may have a greater history of inbreeding than C. hederifolium. In this paper, we examine whether within-population heterozygosity and among-population differentiation on Corsica are consistent with the hypothesis that C. repandum is more inbred than C. hederifolium. Cyclamen hederifolium showed a higher percentage of polymorphic loci, mean number of alleles per locus and mean observed heterozygosity than C. repandum. Cyclamen repandum showed higher among population differentiation (F-ST=0.415) than C. hederifolium (F-ST=0.131). The within-population fixation index was greater in C. repandum (F-IS=0.658) than in C. hederifolium (F-IS=0.329). Cyclamen repandum thus appears to have a greater history of inbreeding than C. hederifolium. The variation in the mating system of the two species is discussed in relation to their sympatric occurrence. and data from previous work on the population genetic structure of island populations of other geographically restricted Cyclamen species.