Current issue: 57(2)
Under compilation: 57(3)
The publication comprises proceedings of a conference held in Helsinki in 1981. Forest tree populations are investigated for population genetic structure, mating systems, mechanisms of genetic adaptation and ecological adaptation. Methods and techniques used in population genetic research of forest trees are presented. Much concern is given to applications by means of forest tree breeding, particularly the seed orchard breeding technique. Generally, the application of population genetics in cultivated forests is discussed.
The PDF includes a preface and the presentations of the conference (25 short papers) in English, and a comprehensive summary of the themes of the conference in Finnish.
The paper discusses the theoretical basis of quantitative analysis of the effect of genotype and environment in forest trees. Perhaps the main problem in the understanding of the laws of intrapopulation variability of the species of woody forest plants is the study of the structure of their populations. It may be characterized by a number of parameters. The intrapopulation variability of quantitative characteristics appears as a result of environmental and genetic factors, but to determine the relative weight of these factors in a concrete case is not easy. The study of the structure of a population by its quantitative characteristics has a wider task: to establish the relevance of the hereditary differences of the individuals of a population. Also, the differences caused by diverse growth conditions and how they are reflected in the level of general phenotypic variability of the quantitative characteristics in a given population has to be identified. The author gives examples of assessment of heritability in forest trees.
The PDF includes a summary in Finnish.
Studies on Finnish Scots pine (Pinus sylvestris L.) plus tree clones by monoterpene and isozyme analyses was undertaken to further investigate mating system, population structure and pollination. Six allozyme systems (3 GOT, 1 GDH and 2 LAP) were properly analysed on the basis of segregation. Monoterpenes were analysed from needle material and segregation in high and low 3-carene content was found to depend on two alleles C and c. Thus, six allozyme systems and one monoterpene system were used as markers in this study.
It was shown that the northern clonal group maintains a much genetic variation as the central or southern clonal groups. The conditional probability of self-fertilization in about 20-year old clones estimated by the multilocus model was 14.1%, of which 8% originate from mating between trees that carry the same alleles to one of the maternal parent at some loci and 6% through self-fertilization.
There was no prominent difference in allele frequency of male gametes that pollinated the very early or very late flowering clones. The northern clonal group has higher a lower frequency of alleles GOT B2 and B3 respectively than of the southern clonal groups. The artificial plus tree selection, particularly in northern Finland, appears to favour heterozygous genotypes for the alleles that control 3-carene content n Scots pine.
The PDF includes a summary in Finnish.
Polymorphisms at a set of eighteen nuclear (nSSR) and chloroplast (cpSSR) microsatellite loci were investigated in sixteen populations of Scots pine (Pinus sylvestris L.) derived from the provenance trial experiment and representative of the species distribution range and climatic zones in Poland. The patterns of genetic variation were compared to the reference samples from the species distribution in Europe and Asia. A similar level of genetic variation and no evidence of population structure was found among the Polish stands. They showed genetic similarity and homogenous patterns of allelic frequency spectra compared to the Northern European populations. Those populations were genetically divergent compared to the marginal populations from Turkey, Spain and Scotland. The population structure patterns reflect the phylogeography of the species and the divergence of populations that most likely do not share recent history. As the analysed provenance trial populations from Poland are diverged in phenotypic traits but are genetically similar, they could be used to test for selection at genomic regions that influence variation in quantitative traits.
Castanea sativa Mill. is one of the most endangered tree species in Iran where it is represented by small fragmented populations in the north of the country. 18 simple sequence repeat (SSR) loci (10 nuclear and 8 chloroplastic) were used to evaluate the genetic diversity and population structure of C. sativa from the Hyrcanian forest. For nuclear SSR, the number of alleles detected per locus ranged from 1 to 5 and observed heterozygosity (HO) was between 0.125 and 1.000. Analysis of molecular variance (AMOVA) indicated a high level of variation within populations (84%) and low levels between populations (16%). Based on structure analysis, the four studied populations were divided into two main clusters that have genetic distance Fst = 0.3. The Shafaroud population was separated in the first cluster, Siyahmazgi, Qalehroudkhan and Veysroud were placed in the second cluster. The UPGMA analysis confirmed the results of Structure analysis, separating the Shafaroud population from the others. The 8 chloroplast SSR loci used to screen the populations showed no polymorphism. In General, low nuclear genetic diversity, no polymorphism in cpDNA and considerable genetic differentiation among populations in short geographical distance represent a serious genetic erosion threat for C. sativa in the Hyrcanian forest, even hinting at an ongoing extinction vortex. Therefore, due to significant decline in genetic diversity, it is essential to introduce constraints protection upon the areas of distribution of all four populations of this species in Iran.