Genetic inventory of European oak populations: Consequences for breeding and gene conservation

The objective of the present study was to characterize the genetic variation in pedunculate oak and sessile oak populations on the basis of isoenzyme markers and to perform a genetic inventory of European oak populations. The results are discussed with special respect to forest tree breeding and conservation of genetic resources. Previous results on oak genetics, summarized in the present paper, are also discussed. The results reveal a relatively high genetic variation among individuals in terms of actual heterozygosities, compared to other plant species. In addition, intrapopulational variation is large. Genetic differentiation among populations of each species is relatively small in general, with certain exceptions. In contrast to earlier results, which suggest smaller differentiation values for pendunculate oak as compared to sessile oak, the present results indicate an opposite trend. The results presented herein suggest that forest tree breeding and silviculture of sessile and pedunculate oak need to take into account large genetic multiplicities. It seems improbable that we can find single stands representing the whole or nearly the whole genetic variation of the species. This would call for a management which is focused on the in situ maintenance of numerous and sufficiently large, locally adapted stands.