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  • Author: Bernd Degen x
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Abstract

We studied the genetic composition of 200 pedunculate oak (Quercus robur) trees at nine nuclear microsatellite gene loci. We sampled nine locations in an area of 1100 km by 400 km in the South-Ural. The question was to analyse the genetic differentiation of the oaks at the south-east edge of the species distribution area. We observed relatively high values of genetic differentiation and fixation (delta=0.387, F ST=0.0652, F ST(Hedrick)=0.407) compared to values from the centre of the species distribution range. Bayesian clustering analysis revealed three genetic groups. Presence of all genetic groups was detected at all locations, but oak trees in the extreme east of the Ural Mountains were genetically most different. We hypothesise that genetic drift influenced the observed pattern.

Abstract

We developed a new set of 25 nuclear (nc), 12 chloroplast (cp) and 7 mitochondrial (mt) SNPs and used it to genotype 371 Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) trees from seven locations in a 200 km by 400 km area in the Russian Far East. One of the locations in an area of 15 km by 25 km east of the city Ussuriusk was analyzed more intensively with 188 collected trees. The genetic differentiation at the nuclear SNPs was small to moderate and for the plastid SNPs it was high when considering all trees from the seven locations. The gene pool distances between locations were for 19 out of 21 pairs statistically highly significant. There was no correlation of genetic and spatial distances. Only three different multilocus-haplotypes could be identified and 42 two-loci-combinations of plastid SNPs could be used to identify them. Conclusions for the practical application such as timber tracking and gene conservation are discussed.

Abstract

Well-adapted, high quality reproductive material is key to the success of forest plantations. Consequently in many countries the collection and trade of forest reproductive material is regulated. Paper documents are usually the only evidence for the origin of forest reproductive material. Certification schemes already established in Germany use genetic inventories to compare reference samples collected at different steps of the chain-ofcustody. A new approach using DNA-fingerprints efficiently controls the origin of seed sources without these multiple reference samples. Only a sample of adult trees within the seed stands is needed. The control is directly made for each suspicious plant or a group of suspicious plants by use of multilocus genotype assignment. We made a field test with samples of adults and seedling from 5 registered seed stands of Quercus robur in Western Germany. Eight highly variable nuclear microsatellites were used to genotype each individual. We found in total 255 different alleles at all loci in the adult populations. The observed levels of genetic variation (Ae= 9.18), genetic differentiation (delta = 0.187) and population fixation (FST = 0.01) were slightly higher than results of similar studies. Individual and group assignment tests were performed with the Bayesian multi-locus approach. The proportion of correctly assigned seedlings was 65% for individuals with completely scored genotypes. In all 5 cases the groups of seedlings were assigned to the correct seed stand and an additional sample of seedlings from another stand could be successfully excluded with a probability test. The conclusion of the field study is that a large scale application of this new approach to control of the origin of forest reproductive material is feasible.