Phylogeographical patterns in the northwestern European moss Scorpidium revolvens (Sw. ex Anonymo) Rubers (Scorpidiaceae, Bryophyta)

Abstract

ABSTRACT Introduction The phylogeography of Scorpidium revolvens (Sw. ex Anonymo) Rubers in northwestern Europe, primarily Scandinavia, was explored. Possibly because of human activity and atmospheric pollution, the species is sparser in the south than in the north, therefore its genetic diversity may be lowest in the south. Methods Relationships within Scorpidium revolvens were evaluated in a network context, based on nuclear ITS and plastid rpl16 data. The regional diversity and haplotype composition of Sc. revolvens, Sc. cossonii (Schimp.) Hedenäs and Sarmentypnum exannulatum (Schimp.) Hedenäs were compared. Key results When the sister species Scorpidium cossonii was used as an outgroup to determine polarity, the basalmost Sc. revolvens haplotype was found to be arctic, and the closest haplotypes to this were found in northern or montane specimens. From a basal grade, three lineages evolved, with differential north and south distribution. The haplotype diversity of Sc. revolvens was lowest in the south, and the haplotype composition of Sc. revolvens, Sc. cossonii and Sarmentypnum exannulatum in the south differed from that in other regions. Conclusions A northern origin for Scorpidium revolvens in Scandinavia is suggested, in common with Sc. cossonii. Wider geographical sampling might confirm a northern origin for Scorpidium. Geographical distributions of the three Sc. revolvens lineages suggest partly separate colonisation routes. Compared with the north, Sc. revolvens in the sparsely populated south has lower haplotype diversity and different haplotype composition. The two other species investigated also had different haplotype composition, and further investigations might determine whether this represents a general pattern in Scandinavia.