Circumarctic dispersal and long‐distance colonization of South America: the moss genus Cinclidium

Abstract

Aim Arctic plant phylogeography has largely focused on seed plants, and studies on other plant groups are necessary for comparison. Bryophytes have a unique life cycle and can be resistant to extreme conditions, suggesting that their phylogeographic patterns may differ from those of vascular plants. We address the history of the bryophyte genus Cinclidium in order to assess: (1) interspecific relationships, (2) whether its current broad circumarctic distribution results from recent dispersal or has been maintained by long-term local survival under severe glacial conditions, and (3) the origin of its bipolar disjunction.Location Arctic/boreal and bipolar.Methods We sequenced three plastid regions (atpH-atpI, rpl32-trnL and clpP1.1-clpP1.2) in 129 accessions covering the entire geographical range of all four described species, and inferred phylogenetic relationships and phylogeographical patterns using maximum parsimony, statistical parsimony and Bayesian inference.Results Cinclidium subrotundum was inferred to be monophyletic, in agreement with its distinct morphology and ecology. The three remaining known species (the haploids C. latifolium and C. arcticum, and the diploid C. stygium) shared a number of closely related or identical haplotypes despite their clear morphological differentiation. In all species, identical haplotypes occurred across the entire circumpolar region, including North Atlantic islands. In the bipolar species C. stygium, the haplotype observed in South America (Tierra del Fuego) was identical to one found in Iceland. Three populations originally referred to C. latifolium harboured highly divergent haplotypes and may represent a new species.Main conclusions The extensive haplotype sharing suggests a polyploid origin of C. stygium from C. arcticum, as well as incomplete lineage sorting and/or hybridization between the two haploids C. arcticum and C. latifolium. We interpret the finding of identical haplotypes over vast areas, including isolated islands, as a result of recent dispersal causing the circumpolar distribution of all species in the Northern Hemisphere and the extreme bipolar disjunction in C. stygium. The patterns in the bryophyte genus Cinclidium resemble those previously documented in arctic-alpine and bipolar vascular plants, suggesting that similar mechanisms have shaped species distributions in bryophytes and higher plants.

Glacial refugia and post-glacial colonization patterns in European bryophytes

“…Few phylogeographic studies of arctic areas have included bryophytes, but the four species in the arctic and boreal moss genus Cinclidium Sw. are found to have identical haplotypes throughout large areas, suggesting recent dispersal as the main mechanism shaping the circumpolar distribution in this genus (Piñeiro et al 2012). It is pres- (Piñeiro et al 2012). It is pres-.…”

Future directions and priorities for Arctic bryophyte research

“…The high dispersibility of bryophytes is supported by phylogenetic (Heinrichs et al 2009;Piñeiro et al 2012;Kyrkjeeide et al 2016a, 2016b), experimental (van Zanten 1978, comparative floristic studies (Miller and McDaniel 2004;Muñoz et al 2004), and field observations (Miller and Ambrose 1976;McDaniel and Miller 2000;Sundberg 2013). Dispersal potential of bryophytes is high due to the production of small spores as well as a suite of specialized (gemmae) and unspecialized asexual diaspores (gametophyte fragments), which may be wind- (Miller and Ambrose 1976;see Schofield 1971 for a detailed review) or animal-dispersed (Parsons et al 2007;Pauliuk et al 2011;Boch et al 2013;Lewis et al 2014).…”

“…If migration is very high, it may overwhelm selective forces and genetic drift, just as it may erase genetic evidence of past demographic events, in which case, distribution of genetic diversity would reflect dispersal related processes and limitations (Piñeiro et al 2012;Kyrkjeeide et al 2016a). Elevational gradients are similar to those across latitudes but occur over shorter distances.…”

“…Sphagnum species tend to show a split between Beringian and Atlantic populations (Szövényi et al 2008;Stenøien et al 2011;Kyrkjeeide et al 2016a), providing evidence that the North American and Eurasian continents act as barriers to dispersal. Other Sphagnum species and four species of Cinclidum are genetically homogeneous across their circum-Arctic to circum-boreal ranges (Piñeiro et al 2012;Kyrkjeeide et al 2016a), suggesting that barriers may act differently, on even closely related species.…”

“…However, our current knowledge of floristic and genetic diversity, evolutionary history, and dispersal in the Arctic is sparse for these ecologically significant plants (but see Piñeiro et al 2012;Kyrkjeeide et al 2014Kyrkjeeide et al , 2016aKyrkjeeide et al , 2016b. This is an increasingly conspicuous and important knowledge gap in the face of rapid climate change in the polar regions (Urban et al 2016).…”