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

Alpine Botany, Jul 2017

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.

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

Alp Botany Phylogeography of Alpine populations of Rhytidium rugosum (Bryophyta) in a European context Lars Hedena¨s 0 1 0 Department of Botany, Swedish Museum of Natural History , 50007, 104 05 Stockholm , Sweden 1 & Lars Hedena ̈s 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 WestSouth-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 WSWmost 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. Break zone; Haplotype; Intraspecific diversity; Private haplotype; Spore-dispersed plants Introduction Numerous investigations have focused on the post-glacial colonization or phylogeographic patterns of different portions of Europe, using molecular evidence (e.g. Brochmann et al. 2003; Hedena¨s 2015; Hewitt 2000; Jaarola et al. 1999; Kyrkjeeide et al. 2014; Parducci et al. 2012; Taberlet et al. 1998) . Several recent studies concerned plants, especially flowering plants, in the European Alps (from here on called ‘the Alps’) (e.g. Gugerli and Holderegger 2001; Scho¨nswetter et al. 2005; Thiel-Egenter et al. 2011) . Source populations for late- to post-glacial colonization of the Alps by plants occurred in glacial refugia in the lowlands, often along the margins of the glaciated area, or on nunataks within the ice shield, and the molecular evidence for such refugia was summarized by Scho¨nswetter et al. (2005). Many flowering plant species of the Alps seem not yet to have colonized all potential habitats due to limited dispersal abilities (Dullinger et al. 2012; Scho¨nswetter et al. 2005) . Where environmental conditions hinder efficient dispersal of species or intraspecific entities of different origins, break zones are found where the turnover in species and/or genotypes within species is markedly higher than elsewhere (Thiel-Egenter et al. 2011) . More break zones exist at the species compared with the genotype level among flowering plants, due to differences in dispersal potential between species (dispersed by seeds) and genotypes (by pollen and seeds). Two major break zones where species and genotype patterns coincide occur around the Aoste valley in the west and around the Adige valley in the east (Thiel-Egenter et al. 2011) . In organisms like bryophytes and fungi, which disperse by spores, sizes of dispersal units are usually in the lower range of pollen grains. This means that the dispersal potentials of both species and intraspecific entities are similar to that of pollen in flowering plants. Spores below c. 20 lm are efficiently dispersed by wind (Wilkinson et al. 2012) and in open, windy environments with few or no trees also small vegetative fragments are easily spread (Flø and Ha˚gvar 2013; Miller and Ambrose 1976) . Phylogeographic patterns of such organisms should thus be more similar to those proposed for small organisms in a meta-community perspective (De Meester 2011) than to the average flowering plant species. Factors that could contribute to intraspecific structure in spore-dispersed organisms include past or present dispersal barriers, the ‘founder takes all’ densitydependent principle (Waters et al. 2013) , niche specialization (Buckley et al. 2013; Mikula´sˇkova´ et al. 2014) , and genetic drift in isolated populations (Frankham et al. 2002). Based on these characteristics and processes, we can hypothesize that break zones in spore-dispersed organisms, both at the species and intraspecific levels, should likely mirror those of genotypes within widespread vascular plants. The number of studies of spore-dispersed organisms that cover large portions of the Alps and its surroundings wit (...truncated)


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Lars Hedenäs. Phylogeography of Alpine populations of Rhytidium rugosum (Bryophyta) in a European context, Alpine Botany, 2017, pp. 197-209, Volume 127, Issue 2, DOI: 10.1007/s00035-017-0191-0