Intraspecific genetic variation in selected mosses of scandinavian interglacial refugia suggests contrasting distribution history patterns

Abstract

Three pleurocarpous mosses were studied to explore the haplotype diversity patterns in a Scandinavian system of interglacial refugia in which low-competitive species of calcareous or base-rich habitats occur. Hypnum bambergeri and H.vaucheri displayed little variation across Scandinavia. For the third species, Drepanocladus turgescens, an analysis of molecular variance showed that two S Scandinavian lowland regional populations were significantly different from each other and differed or almost differed (Gotland vs. Jämtland, according to pair-wise ΦPT) from the populations of the Scandinavian mountain range and Svalbard. Haplotype diversity displayed little variation among regional populations, and did not reflect the higher frequency of sexual reproduction in southern than in mountain populations. A coalescent-based analysis (LAMARC) indicated immigration into the population now found in the lowlands from that represented in the mountains. This is contrary to that found in Rhytidium rugosum in an earlier study and, together with the fact that sporophytes are produced almost exclusively in the lowlands, speaks against this direction of post-glacial migration. Therefore, if the LAMARC results reflect migration patterns, these most probably reflect events that occurred earlier. Taken together with the results on R.rugosum, this study emphasizes the fact that moss species having similar distribution patterns reached these distributions in partly different ways.