Genotypic structure in clonal Rhododendron ferrugineum L-(Ericaceae) populations: origin and maintenance

Genotypic structure of a closed population of the clonal ericaceous shrub R hododendron ferrugineum is examined in the light of two independent studies previously conducted on this species. In the first study, spatial distribu tion of genotypes in the closed population was inferred from the amplified fragment length polymorphism (AFLP) procedure. Age of clones was estimated using their spatial extent and the annual growth rate of shoots. In the sec ond study, ramet demography was studied in the three most representative st ages of shrub invasion on two different sites, including the site where the population investigated by AFLP grew. The demographic data recorded were t he area occupied by ramets and ramet age, and from this information the dev elopmental pattern of Rhododendron populations was determined. Additional d ata such as genet density and distance between genets were calculated. These two sources of information allow us to propose that all or most of th e clones detected in the closed population established at the early success ional stage, and that the present genotypic structure was established sever al hundred years ago, long before the population reached total closure. Hyp otheses concerning the future development of this genotypic structure are d iscussed.