Phylogeography of Alpine populations of Rhytidium rugosum (Bryophyta) in a European context

Abstract

The phylogeography and possible origins of the moss Rhytidium rugosum (Hedw.) Kindb. in the European Alps are studied based on information from the nuclear internal transcribed spacers 1 and 2 and a portion of the gene region for glyceraldehyde 3-phosphate dehydrogenase for 364 European specimens. Seventy-three Alps specimens were sampled from W Switzerland to W Austria, and were divided into four regional populations along a West-South-West (WSW) to East-North-East (ENE) gradient. These populations were compared with similar ones previously studied in other parts of Europe. The ENE-most Alps population, located ENE of the Adige break zone, deviates genetically from the other three. The two WSW-most populations of the Alps appear to be relatively isolated from most of the European populations outside the Alps, whereas the two ENE ones are similar to populations of northern Scandinavia. Populations in between the Alps and the Scandinavian mountain range deviate from those to the north and south, possibly due to low effective population sizes, earlier bottleneck events, or colonization from different source populations. Haplotype diversity and number of private haplotypes are marginally higher in the Alps than in Scandinavia. It is suggested that European Rhytidium originated from late glacial maximum refugia in (1) E-NE Europe, (2) in between the Late Glacial Maximum ice shields of Scandinavia and the Alps, and (3) S, SW, and W of the Swiss Alps. Those of the E Alps potentially originated mainly in E-NE Europe and those of the W Alps in the S, SW, and W.