Genetic diversity and structure of Silver fir (Abies alba Mill.) at the south-eastern limit of its distribution range

Abstract

Genetic diversity and structure of Silver fi r (Abies alba Mill.) at the south-eastern limit of its distribution range. Ann. For. Res. 62(2): 139-156.

The Pattern of Genetic Variation, Survival and Growth in the Abies alba Mill. Population within the Introgression Zone of Two Refugial Lineages in the Carpathians

“…Thus, the climatic gradient might affect gene pools and favor less drought-sensitive genotypes in the eastern region. Despite worsening climatic conditions in the eastern gradient, the present analysis and data by Gömöry et al [30] and Teodosiu et al [35] indicate that genetic variation increases toward the meeting zone of the refugial lineages in the Western Carpathians from west to east and in the Romanian Carpathians in the opposite direction. This strongly corroborates the hypothesis that the observed genetic and phenotypic variation is attributable to pollen-mediated influence.…”

“…Investigations on maternally inherited mitochondrial DNA in A. alba have confirmed the presence of two highly conservative haplotypes at the mitochondrial nad5-4 locus, which were assigned to two glacial refugial areas [26,[28][29][30]35] and only one western haplotype in Poland [60,61]. The results also confirm considerable within-population variation in A. alba (97%), which is typical for wind-pollinated species over a continuous distribution range [62,63].…”

“…Although the sigmoid model estimates were 199 and 201 km, respectively, the cluster proportions changed in a continuous manner, and the pollen-mediated influence of the eastern lineage was detectable in the western subpopulations at a distance of at least of 300 km. A recent study by Teodosiu et al [35] suggests a similar gradient in the Romanian Carpathians; the highest level of genetic diversity, in both allelic richness and expected heterozygosity, was found in the northern and outer Eastern Carpathians, close to the contact zone of the two maternal lineages. In contrast to our study, in the research of Ballian et al [74] in Croatia and Bosnia, A. alba subpopulations located east of the contact zone did not manifest any distinct cline variability in genetic parameters.…”

“…Admittedly, earlier studies using isoenzyme markers in Italy [64], Poland [65], the Balkans [66] and Slovakia [67] suggested a lower within-population proportion of about 80%. However, the results obtained for nuclear markers [35,41,[68][69][70][71], because of their high polymorphism, selection neutrality and co-dominant character, are more appropriate for characterizing genetic diversity.…”

“…Pollen-mediated gene flow over the boundary between lineages would be expected to lead to the enrichment of gene pools by alleles from the counterpart lineages and consequently to increased allelic richness at nuclear loci in the subpopulation located close to the boundary. In fact, Gömöry et al [30], and recently also Teodosiu et al [35], found that, within the Balkan lineage, genetic diversity and allelic richness increase towards the meeting point. Nevertheless, no such trend was observed for the western lineage, and Gömöry et al [30] attributed this to the short geographic trend in the data set.…”