Phylogenetic structure in the Sphagnum recurvum complex (Bryophyta: Sphagnaceae) relative to taxonomy and geography

Premise The Sphagnum recurvum complex comprises a group of closely related peat mosses that are dominant components of many northern wetland ecosystems. Taxonomic hypotheses for the group range from interpreting the whole complex as one polymorphic species to distinguishing 6–10 species. The complex occurs throughout the Northern Hemisphere, and some of the putative species have intercontinental ranges. Our goals were to delimit the complex and assess its phylogenetic structure in relation to morphologically defined species and intercontinental geography. Methods RADseq analyses were applied to a sample of 384 collections from Europe, North America, and Asia. The data were subjected to maximum likelihood phylogenetic analyses and analyses of genetic structure using the software STRUCTURE and multivariate ordination approaches. Results The S. recurvum complex includes S. angustifolium, S. fallax, S. flexuosum, S. pacificum, and S. recurvum as clades with little evidence of admixture. We also resolved an unnamed clade that is referred to here as S. “pseudopacificum.” We confirm that S. balticum and S. obtusum are nested within the complex. Species with bluntly acute to obtuse stem leaf apices are sister to those with acute to apiculate leaves. Most of the species exhibit some differentiation between intraspecific population systems disjunct on different continents. Conclusions We recognize seven species in the amended S. recurvum complex, including S. balticum and S. obtusum, in addition to the informal clade S. “pseudopacificum.” Although we detected some geographically correlated phylogenetic structure within widespread morphospecies, our RADseq data support the interpretation that these species have intercontinental geographic ranges

Disentangling knots of rapid evolution: origin and diversification of the moss order Hypnales

The Hypnales are the largest order of mosses comprising approximately 4200 species. Phylogenetic reconstruction within the group has proven to be difficult due to rapid radiation at an early stage of evolution and, consequently, relationships among clades have remained poorly resolved. We compiled data from four sequence regions, namely, nuclear ITS1–5.8S–ITS2, plastid trnL–F and rps4, and mitochondrial nad5, for 122 hypnalean species and 34 species from closely related groups. Tree topologies from both Bayesian and parsimony analyses resolve the order as monophyletic. Although inferences were made from fastevolving genes, and despite strong phylogenetic signal in the nuclear ITS1–5.8S–ITS2 data, monophyly, as well as backbone nodes within the Hypnales, remains rather poorly supported except under Bayesian inferences. Ancestral distribution based on Bayesian dispersal-vicariance analysis supports a Gondwanan origin of the Hypnales and subsequent geographical radiation in the area of the former Laurasian supercontinent. Reconstruction of historical biogeography is congruent with mainly tropical and Gondwanan distributions in the sister groups Hypnodendrales, Ptychomniales, and Hookeriales, and with the dating for the oldest pleurocarp and hypnalean fossils. We contrast groupings in the phylogenetic tree with recent classifications and other phylogenetic inferences based on molecular data, and summarise current knowledge on the evolutionary history of, and relationships among, the Hypnales