Phylogeography of the threatened peat moss Sphagnum wulfianum Girg. with emphasis on northern Europe

Abstract

The species distribution in northern Europe is influenced by the last glaciation. An increasing number of phylogeographic studies reveal possible glacial refugia and colonization pattern for different species, however, little is known of migration routes of mosses. The phylogeography of Sphagnum wulfianum have been studied to find out how genetic variation is distributed in Europe and possible immigrations routes into Scandinavia after the last glaciation. Genetic diversity statistics show that genetic variation in microsatellite loci is extremely low (He=0.028±0.09) in this species and that populations are highly differentiated (FST=0.74). Low genetic variation may bedue to one or several bottlenecks in the past and/or colonization of northern Europeby repeated founder events. Methods based on Bayesian approaches (STRUCTURE)and coalescence theory (IM and MIGRATE) show that there is two main genetic clusters, and that these diverged recently (1812 years ago). There may have been two immigration routes into Scandinavia after the last glaciation, one from south-east across the Baltic Sea and one from east through Russia and Finland.