Genotypic differentiation between the two related peat mosses, Sphagnum rubellum and S. capillijolium in northern Europe

Abstract

Isozyme electrophoresis was used to study the genetic relationship between the morphologically overlapping taxa Sphagnum rubellum and S. capillijolium. Multilocus genotypes were determined for over 1300 plants representing 36 sites in Scandinavia, Great Britain and southern Germany. In total 121 multilocus genotypes were recorded. The 14 most abundant genotypes constituted ca 70% of the shoots analysed. From the genotypic data a species index (SI) was constructed to test the single- and two-species hypotheses. At the molecular level, a division corresponding to the two taxa was evident. S. rubellum was recorded from wet, ombrotrophic to weakly minerotrophic bog/poor fen habitats, while S. capillijolium was usually found in drier, minerotrophic forest/(sub) alpine heath habitats. Few individuals (1.6%) had mixed isozyme marker alleles, and these tended to occur in mixed populations from mire margins. Sphagnum capillijolium was only recorded at one out of eight British sites. Species concepts and methods for integrating genetic data with morphological data are discussed.