Sanna Huttunen
Department of Biology, University of Turku, Finland
The Hypnales are the largest moss order comprising circa 4200 species, i.e. 1/3 of all mosses. Phylogenetic reconstruction of the group has proven to be difficult due to rapid radiation at an early stage of their evolution, but the most studies applying molecular systematic methods favor its position as a crown clade in the phylogeny of mosses. Within the order, however, relationships among groups have remained poorly resolved. The most recent phylogenetic inference is based on 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 resolve the order as monophyletic, although monophyly, as well as the backbone nodes within the Hypnales, gained significant support only under Bayesian inferences. The phylogenetic tree differs only in few details from recent classifications, but familial relationships especially among the apical crown clade within the Hypnales were mainly unsupported. Ancestral distribution based on Bayesian dispersal-vicariance analysis support 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. Scattered fossil data, unique character combinations in some of the fossil pleurocarps and lack of a well-supported phylogeny, however, still hamper testing diversification events using molecular dating. In the presentation I will summarize current knowledge on the evolutionary history and relationships among the Hypnales and present an overview of the recent fossil data on pleurocarpous mosses. In light of these two sources of the information I aim at discussing evolution of the Hypnales and point out potential directions for future research.
