To evaluate the genetic diversity of red raspberry, pedigrees of 91 cultivars released since 1960, were traced. These cultivars were derived from 35 founding clones representing 9 Rubus species. The cultivars were clustered according to the genetic contribution of their founding clones. The resulting groups could be related to the geographical origin of the cultivars within them. They could be distinguished by the contribution of the founding clones. Each group had either 1 founding clone which contributed 40% of its germplasm to the group or 2 or 3 clones which contributed 20%.
Three strategies are suggested to maintain and increase the genetic diversity of the world's raspberry breeding populations: 1) combine partially or completely unrelated cultivars; 2) introduce unselected R. idaeus clones and 3) introduce other Rubus species into the breeding population.