XVI International Botanical Congess

Genetic variation is low in Arnica montana, a rapidly declining clonal species in The Netherlands. Population size was positively correlated with the proportion of polymorphic loci, the number of effective alleles and the expected heterozygosity but not with the observed heterozygosity. In smaller populations an excess of heterozygotes was found. F-statistics showed a high level of differentiation between populations, suggesting a low level of gene flow. Natural seed production and offspring fitness (seedling weight, the number of flowering stems and flowerheads, survival and total fitness) was positively correlated with population size. Populations with low genetic variation gave significantly smaller seedlings. Implications for conservation will be discussed.