I. V. Petrova

Phylogenogeography and genotaxonomy of Pinus sylvestris L. populations

The phylogenogeographic structure, polymorphism, and differentiation of Pinus sylvestris L. have been studied for the first time by means of allozyme analysis of 143 populations along a network of transects covering the entire species range. The results show that the species in general is characterized by a significant level of differentiation, regardless of its relative uniformity in northern and central parts of the range. Nei’s genetic distances between populations and their gradients in the extreme southern parts of the range, where it has an insular pattern, are seven to eight times greater than in the northern, “glacial” zone. Three Pleistocene refugia for the species have been revealed in the Balkans, Southern Urals, and Northern Mongolia. Using analysis of genetic distances between 18 phylogeographic regions and an original genosystematic scale, one subspecies, five geographic races and nine geographic population groups have been distinguished in the P. sylvestris L. species structure.

Genetic Differentiation of Pinus mugo Turra and P. sylvestris L. Populations in the Ukrainian Carpathians and the Swiss Alps

The allozyme analysis of six local populations of Pinus mugo Turra and six populations of P. sylvestris L. in the Ukrainian Carpathians, Swiss Alps, and Schwarzwald has shown a higher polymorphism and greater interpopulation differentiation of the Carpathian group of P. mugo populations compared to the Alpine group (Nei’s genetic distance DN78 at the level of geographic population group is −0.023). A genetic differentiation of DN78 = 0.049 between these populations, which are isolated by a distance of more than 1000 km, has been found. This confirms the existence of the subspecies P. mugo ssp. mugo and P. mugo ssp. uncinata in the Carpathians and Alps, respectively. The hypothesis is put forward that the former subspecies has been formed in the Balkans and the latter, in the Pyreneans. It has been demonstrated that regional populations and geographic groups of P. sylvestris are less differentiated than those of P. mugo.

A system of Pleistocene refugia for Pinus sylvestris L. in the southern marginal part of the species range

An allozyme analysis of 67 Pinus sylvestris L. populations distributed over the entire species range has provided a basis for determining locations of 12 hypothetical Pleistocene refugia (HPRs) in its southern marginal part and estimating their relative contributions to the gene pools of seven phylogeographic population groups (PPGs) in the glaciated zone of the range. Using Nei’s (1978) minimum genetic distances (DN78 < 0.015) reflecting similarities and differences in allele frequencies between PPGs and the refugia, it has been shown that the main contributions to the P. sylvestris gene pool in Central Europe, Scandinavia, and the Russian Plain were probably made by the Balkan and Southern Ural refugia, and in Western and Central Siberia, by the Southern Ural, Turgai, and Southern Siberian mountain refugia.

Gradient Genogeographic Analysis of Pinus sylvestris L. Populations in Europe

Gradients of Neis genetic distances between 15 samples of Pinus sylvestris L. trees were analyzed along three submeridional transects, from Scandinavia to the Mediterranean and Transcaucasia. As a result, distinct chorogenetic differentiation was revealed between the populations of this species growing in climatically specific regions of northern and southern Europe. Considerable Neis distances (DN = 0.045–0.056) and their gradients, combined with differences in stable phenotypic characters (the composition of monoterpenes and morphological parameters of cones) determined at the Pyrenean and Caucasian mountain borders, suggest that the P. sylvestris species structure includes two South Eurasian subspecies, the Pyrenean P. sylvestris L., ssp. iberica Svoboda and the Transcaucasian P. sylvestris L., ssp. hamata (Stev.) Fomin.

Genetic and phenotypic differentiation of Calluna vulgaris (L.) Hull in Pritobolie and Europe

Geographic variation and differentiation of the chloroplast DNA haplotypes and morpho-anatomical leaf parameters were assessed in a number of eastern European groups of Calluna vulgaris (L.) Hull. populations and in the Pritobolien group of populations of this species in Western Siberia, which have long been isolated from the European populations. Sharply pronounced genetic and phenotypic distances and their gradients between the Pritobolien and European population groups were revealed. These distances were many times higher than those between the relatively homogeneous eastern European groups. The data obtained generally supported the hypothesis on the phenogenetic divergence of the Pritobolien marginal populations of C. vulgaris from the European, probably at the subspecies level.

Genetic divergence of eastern European and Tobol populations of Calluna vulgaris (L.) Hull.

Analysis of geographic variation of chloroplast DNA in the eastern European and western Siberian (Tobol) groups of Calluna vulgaris populations isolated from each other for a long period of time has revealed distinct differentiation between them. It has been shown that three populations growing in the Russian Plain and Karelia share two haplotypes characteristic of central Europe, while three Tobol populations contain one haplotype F occurring in Sweden. These results confirm the hypothesis of genetic divergence between the Tobol and eastern European groups of C. vulgaris populations.

Competition factors of edificator tree stand: Quantitative analysis and synthesis

To analyze and quantitatively estimate the contribution of different factors of competition from the edificator tree stand to its effect on plants comprising the lower forest vegetation layer, a set of ecophysiologically based indices of root, light, and integrated competition has been proposed and tested. The results obtained in pine and spruce forests forests of Western Siberia and the Urals show that the growth of the conifer undergrowth is more closely correlated with the index of root competition, and that of heather (Calluna vulgaris (L.) Hull.), with the index of light competition from the edificator tree stand. Moreover, the correlation of their growth with the integrated competition index is 15–25% stronger than the correlation with the indices of root and light competition, irrespective of forest type.

Gradient analysis of the chrogenetic structure of lowland and highland scotch pine populations

Gradients of genetic distances (GGDs) between 26 adjacent cenopopulations of Scotch pine (Pinus sylvestris L.) along the transects through the distinct landscape-ecotopic isolation borders were analyzed graphically. The results made it possible to reveal and quantitatively estimate gradients and borders of gene-pool structural patterns in populations of this species in the central part of Northern Eurasia. In lowland areas, the most distinct borders were found between pine populations growing on dry lands and bogs (Pineta sphagnosa) in the forest zone of the Transural region, as well as between the Arakaragaiskii and Amankaragaiskii island pine forests in the steppe zone (Northern Turgai). In highland areas (the Urals and the Carpathians), the greatest GGDs were observed between low-mountain (about 600 m above sea level) and middle-mountain (850–900 m) populations. Analysis of GGDs is a promising gene-geographic method for determining population borders and studying the chorogenetic structure of species.

Reproductive isolation and disruptive selection as factors of genetic divergence between Pinus sylvestris L. populations

Generalizations are made on the basis of results obtained in the course of long-term, stationary quantitative studies on phenogenetic divergence of P. sylvestris populations growing in an upland bog and the adjacent dry land area in the pre-forest-steppe zone of Western Siberia. Contrasting differences between the two edaphoecotopes and almost complete phenological reproductive isolation of populations from year to year are demonstrated. It has been found that root morphogenesis in the F1 progeny of pine from the bog population grown under uniform ecological conditions in the dry land area is characterized by elimination of the vertical phenotype, with the alternative lateral phenotype type being dominant in 7- to 22-year seedlings. Significant allozyme differentiation and distinct chorological boundary between the dry-land and bog populations have been revealed. The hypothesis of their genetic divergence in the Holocene is proposed, with this phenomenon being explained by the cumulative effect of disruptive selection and strict reproductive isolation in two contrasting environments.

Insularization and polymorphism in marginal island populations of Pinus sylvestris L.

Comparative allozyme analysis of 26 marginal island populations of Pinus sylvestris L. and 20 populations from the center of the species range has confirmed, at the species level, the Wright-Dubinin “island model” of automatic genetic processes and Mayr’s hypothesis about homozygotization of small isolated populations at range boundaries. It has been shown that the polymorphism of isolated populations sharply decreases when their area is reduced below 15–20 km2 and increases to the level observed in the center of the range when the population area exceeds 50–100 km2. A chorogenetic classification of marginal P. sylvestris populations is proposed.