Contrasting phylogeographic patterns in Sphagnum fimbriatum and Sphagnum squarrosum (Bryophyta, Sphagnopsida) in Europe

Abstract

Summary• The chloroplast phylogeography of two peat mosses ( Sphagnum fimbriatum and Sphagnum squarrosum ) with similar distributions but different life history characteristics was investigated in Europe. Our main aim was to test whether similar distributions reflect similar phylogeographic and phylodemographic processes.• Accessions covering the European distributions of the species were collected and approx. 2000 bp of the chloroplast genome of each species was sequenced. Maximum parsimony, statistical parsimony and phylodemographic analyses were used to address the question of whether these species with similar distributions show evidence of similar phylogeographic and phylodemographic processes.• The chloroplast haplotypes of the currently spreading species S. fimbriatum showed strong geographic structure, whereas those of S. squarrosum , which has stable historical population sizes, showed only very weak geographic affinity and were widely distributed.• We hypothesize that S. fimbriatum survived the last glaciations along the Atlantic coast of Europe, whereas S. squarrosum had numerous, scattered refugia in Europe. The dominance of one haplotype of S. fimbriatum across almost all of Europe suggests rapid colonization after the last glacial maximum. We hypothesize that high colonizing ability is an inherent characteristic of the species and its recent expansion in Europe is a response to climate change.

Modeling Species Distributions from Heterogeneous Data for the Biogeographic Regionalization of the European Bryophyte Flora

“…In the genus Polytrichum for instance, van der Velde & Bijlsma [55] found no geographic structure in patterns of genetic variation across the continent. In Sphagnum fimbriatum and Radula lindenbergiana , the dominance of one haplotype suggests rapid post-glacial dispersal, sufficient to prevent substantial genetic differentiation among populations by genetic drift and to wipe out an initially present genetic structure resulting from the last glacial periods [56], [57]. This is consistent with previous studies reporting rapid community shifts from range dynamics analyses [58], [59] and stratigraphic analyses of macro-remains preserved in peat [60], [61].…”

Glacial refugia and post-glacial colonization patterns in European bryophytes

“…Several refugia have been hypothesized for Sphagnum squarrosum Crome, and three genetic clusters are found in this species (Szövenyi et al 2006(Szövenyi et al , 2007. However, the clusters are only weakly structured in Europe, possibly due to extensive gene flow.…”

“…However, the clusters are only weakly structured in Europe, possibly due to extensive gene flow. Sphagnum fimbriatum Wilson on the other hand, is found to be highly structured in one 'Atlantic' and one 'non-Atlantic' clade (Szövenyi et al 2006(Szövenyi et al , 2007. The Atlantic clade likely survived the LGM along the western coast and is currently found from southern England to northern Spain, while the non-Atlantic clade is widespread in Europe and probably recolonized the continent rather rapidly after the LGM.…”

Testing the cause of the Sphagnum austinii (Sull. ex Aust.) decline: Multiproxy evidence from a raised bog in Northern Ireland

“…The use and study of contemporary and subfossil plant DNA may have important implications for linking the modern and fossil specimens of this species and understanding its palaeoecology and phylogeography (e.g. Szövényi et al, 2006;Suyama et al, 2008). This may offer further insights into why Sphagnum austinii suffered such a dramatic loss in the peatlands of Britain and Ireland.…”