2 Material and Methods
2.1 Study genus
Larix Mill. is the most abundant genus in boreal coniferous
forests of Eurasia and Larix species cover 70% of the forest
biome globally (Abaimov 2010). Larches are well adapted to the harsh
climate conditions, that is, cold winters to below −40 °C and short
summers with only 60–90 days exceeding the freezing point (Franz 1973).
According to different taxonomic systems, there are different opinions
regarding the number of larch species and the boundaries of their
habitants (Mayr 1906; Dylis 1961; Bobrov 1972). The distribution areas
of some Larix species overlap and larches can hybridize easily in
natural habitats (Semerikov et al. 2007; Abaimov 2010). This especially
applies to the Siberian larch species. For this study, following Bobrov
(1972), we recognize three species of Larix across their Siberian
distribution from east to west, L. sibirica Ledeb., L.
gmelinii (Rupr.) Rupr., and L. cajanderi Mayr, although we
acknowledge there might be considerable hybridization between the
several species and varieties. The natural distribution of Siberian
larch species extends from west to east in large, relatively discrete
ranges with hybridization occurring in the boundary zones (Abaimov
2010).
2.2 Study area and sample collection
The study area includes arctic and subarctic areas located in the
forest-tundra transition zone in Siberia. The sites are located in
Siberia from the Ural Mountains in the West, followed by the Taymyr
Peninsula, to the Lena Delta and the Verkhoyansk Range reaching to
Chukotka in the Far East; as well as Kamchatka in the southeast, via
Magadan and southern Yakutsk to the Altai Mountains (c. 50–80°N;
50–180°E).
For genetic analyses, fresh needles from natural populations ofLarix sibirica , L. gmelinii , and L. cajanderi were
taken during summer fieldwork (2011–2021) (Fig. 1). Samples were
selected to cover a wide distribution area of Siberia. Needle samples
were dried on silica gel during fieldwork and stored at 4°C. In total,
148 individuals were processed for which the identifier, geographic
position, and height were recorded (Appendix S1).