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Tuesday June 07, 11:00 AM - 3:00 PM

Authors:
Weronika Barbara Żukowska ¹; Błażej Wójkiewicz ¹; Andrzej Lewandowski ¹; Witold Wachowiak ^1,2

Affiliations:
1) Institute of Dendrology, Polish Academy of Sciences, Kórnik, Poland; 2) Institute of Environmental Biology, Adam Mickiewicz University in Poznań, Poland

Keywords:
Population history

Scots pine (Pinus sylvestris L.) is the most widespread representative of conifers, native to Eurasia. It is one of the most important forest-forming tree species in the northern hemisphere. Genetic conservation of Scots pine seems to be of low priority because of its very wide distribution spanning several climatic zones. However, the effects of over century-long cultivation and increased mortality due to climate changes make it necessary to describe the genetic resources of Scots pine in more detail.

Using 16 nuclear microsatellite markers, we investigated the genetic variation of 62 Scots pine populations (1,289 individuals) located in Europe and Asia. We confirmed the high overall genetic variation and low interpopulation differentiation (F_ST = 0.029, R_ST = 0.042; p < 0.001) of this species. The average observed heterozygosity was equal to the average expected heterozygosity (H_O = H_E = 0.525). Lower genetic variation was found in the British Isles, a few mountain populations from Poland, two Italian stands located south of the Alps, and most locations from Eastern Siberia. Private alleles were found mostly in southern regions that are considered the glacial refugia of the species. Central and Northern Europe seems to have been recolonized mainly by Balkan migrants. It appears, however, that other so-called cryptorefugia from higher latitudes, as well as populations from south-eastern regions, could have also contributed to the genetic variation observed in Europe. On the other hand, the populations far east can be largely divided into two groups with the lowest genetic variation in Eastern Siberia.

We detected a significant phylogeographic structure among populations and geographic regions. This means that stepwise-like mutations have contributed to the genetic differentiation of Scots pine. Bayesian assignment and the Principal Coordinates Analysis (PCoA) showed clear differences between populations from Europe and Asia. Only the sites located west of the Urals were genetically more similar to Central and Northern European populations. The test for the deficiency in M-Ratio revealed that most stands have suffered from the past genetic bottleneck. We hypothesize that the lack of genetic structure among Northern and Central Europe, including some western stands, is at least partially the result of past human activities related to the transfer of germplasm in the 19^th and in the early 20^th century.

The research was financed by the Institute of Dendrology of the Polish Academy of Sciences and the Polish National Science Centre (grant no. 2016/21/N/NZ9/01499).