Haplotype variation of relevance to global and European phylogeography in Sarmentypnum exannulatum (Bryophyta: Calliergonaceae)

Haplotype variation is explored for Sarmentypnum exannulatum (Schimp.) Hedenas, based on the nuclear ITS, and the chloroplast trnL-trnF, rp/16 and tRNA-Gly in 179 specimens (176 for chloroplast markers). The focus is Europe (124 samples), and especially Scandinavia (79), but most regions of the species' distribution area except northern Eurasia were sampled. Haplotype variation appears greater in Scandinavia than in Central Europe, with five of the European haplotype groups found only in Scandinavia compared with one unique to Central Europe. The Central European haplotype group probably survived the glaciations in one or several of the well-known refugia of the northern Mediterranean, but this seems unlikely for the Scandinavian haplotypes. The latter could have survived in northern refugia or immigrated from the east or north-cast. On a global scale, several haplotype groups have restricted distributions, which could be due to sparse sampling in some regions, or the evolution or extinction of haplotypes. Some haplotypes were perfectly bipolar, whereas the species its a whole is imperfectly bipolar. These were absent from more southern parts of the northern temperate zone and from the sampled tropical mountains. It thus seems unlikely that representatives of these haplotypes dispersed from north to south (or vice versa) by stepwise migration.