Genetic diversity and differentiation of 12 native populations of European larch (Larix decidua Mill.) from Piedmont (North-Western Italy) were estimated by means of variation detected in 11 enzyme systems encoded by 20 loci. The trees showed relatively large genetic variability but small interpopulational variation. The expected heterozygosity ranged from 0.239 to 0.279 (mean 0.254); on average, more than 66% of the loci per population were polymorphic and the number of alleles per locus was 2. Only 3.3% of the observed genetic diversity was due to differentiation among populations, and the mean value of genetic distances, as measured by pairwise FST, was 0.033, with a maximum of 0.087. A positive correlation was found between genetic and geographic distances. The low interpopulational variability suggests the presence of a single gene pool and a lack of barriers to gene flow between the populations. Principal components analysis showed that the first two principal components accounted respectively for 27 and 18% of the total variation of allele frequencies. The Navette population was clearly different from the others, while, unexpectedly, the Formazza population appeared to be genetically close to other populations in spite of its geographical isolation. The results of the study provide useful information for in situ preservation of genetic variability and for identification of the most valuable stands for production of high quality seed.
Genetic variability among European larch (Larix decidua Mill.) populations in Piedmont, North-Western Italy
BELLETTI, Piero;LANTERI, Sergio;
1997-01-01
Abstract
Genetic diversity and differentiation of 12 native populations of European larch (Larix decidua Mill.) from Piedmont (North-Western Italy) were estimated by means of variation detected in 11 enzyme systems encoded by 20 loci. The trees showed relatively large genetic variability but small interpopulational variation. The expected heterozygosity ranged from 0.239 to 0.279 (mean 0.254); on average, more than 66% of the loci per population were polymorphic and the number of alleles per locus was 2. Only 3.3% of the observed genetic diversity was due to differentiation among populations, and the mean value of genetic distances, as measured by pairwise FST, was 0.033, with a maximum of 0.087. A positive correlation was found between genetic and geographic distances. The low interpopulational variability suggests the presence of a single gene pool and a lack of barriers to gene flow between the populations. Principal components analysis showed that the first two principal components accounted respectively for 27 and 18% of the total variation of allele frequencies. The Navette population was clearly different from the others, while, unexpectedly, the Formazza population appeared to be genetically close to other populations in spite of its geographical isolation. The results of the study provide useful information for in situ preservation of genetic variability and for identification of the most valuable stands for production of high quality seed.
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