Genetic diversity and ecotypic differentiation in arctic and alpine populations of Polygonum viviparum

In high arctic, subarctic, and alpine populations of Polygonum viviparum L. (Bistorta vivipara [L.] S.F. Gray) intermediate to high levels of genetic diversity were detected. In lowland populations in the Alps, which are outside of the typical ecological range of P. viviparum, none or very little genetic variability was found. Most genotypes were restricted to one or a few populations. High arctic, subarctic, and alpine populations had no genotype in common. Plants from Scandinavia needed considerably longer photoperiods for floral induction than plants from lower latitudes (Alps). The Scandinavian plants proved to be genetically adapted to the long, continuous daylight in summer at high latitudes. Stem length differences of lowland and highland clones of the Alps persisted under identical conditions in culture. Polygonum viviparum reproduces almost exclusively asexually by bulbils, but the development of seeds can occasionally be observed even in arctic and alpine populations. The differentiation of ecotypes and medium to high levels of genetic diversity in arctic and alpine populations is thought to be the result of occasional sexual reproduction.