Origin and genetic diversity of introduced species (larch and beech) in Norway

Yakovlev I.A., Myking T.

Norwegian Forest and Landscape Institute, Ås, Norway. igor.yakovlev@skogoglandskap.no

The common beech (Fagus sylvatica) and the European larch (Larix decidua) are non-autochthones species introduced in Norway. The world's northernmost beech population is located at Seim on the west coast of Norway at 60° N, about 330 km from the nearest occurrence of spontaneous beech. Most probably they were planted artificially between 500 and 1000 AD, during the Viking age, on the relatively small areas and their geographic origin has been a matter of interest for at least a century. The oldest larches had been planted in 1800^th in the avenue of Sandvika, from where it spread throughout the whole Tingvoll area.

Here we are reporting the using of molecular markers for tracing of origin of larch and beech populations in Norway and study of their genetic diversity. Methodically, the study was based on comparison of mitochondrial (mt), chloroplast (cp), and nuclear (n) DNA polymorphisms on the same set of individuals of larch and beech, growing in Norway and their potential ancestors from the Great Britain and Denmark (for Beach), chosen from previous literature search. We used inter-simple sequence repeat (ISSR) markers for nDNA and polymerase chain reaction–restriction fragments length polymorphism (PCR–RFLP) markers for mitochondrial and chloroplast DNA.

Larch. For cytoplasmic markers we study two regions in cpDNA (VL and IC2) and one region in mtDNA (Cox1). In total 23 chloroplast haplotypes were scored with just one monomorphic mitochondrial haplotype. Using six ISSR primers, a total 65 fragments were scored, 9 bands were monomorphic and 56 were polymorphic.

Genetic diversity computed for each location of individuals was sufficiently high. Scotland and Norwegian larch samples did not differ considerably in total genetic diversity with the average h values computed for Scotland is 0,25 (0,22 for haplotype) and for Norway – 0,24 (0,18). The present larch populations in Norway have high level of interpopulation differentiation confirmed by the relatively high G_ST values (0,31) and Θ_P (F_ST) = 0,24, with bootstrap 95% confidence limits (0,20 – 0,33). We could conclude that most probably larches to Sandvika alley were transferred from several sources, including: Dunkeld, Lude, Dunphail, Linley and Blair Athol locations in Scotland.

Beech. Looking for origin of beech populations we studied 7 Norwegian (4 from Seim), 5 Great Britain and 4 Denmark populations. No variation in maternally inherited genes (chloroplast DNA, 8 regions studied) was revealed. It most likely consists of a single haplotype of East European origin. Using six ISSR primers, a total 71 polymorphic fragments were scored. The relatively high genetic variation in the Seim beech populations (h=0,191 – 0,208, H_T=0,251) implies establishment by many parents seeds, as pollen contamination from outside can be excluded. Clustering of populations on the base of marker frequencies shows that all 4 Seim populations most closely related to Denmark populations. We conclude that most probably these populations were planted with the seed sourced from Julland area (Denmark)