|Tuesday, July 06|
The Backbone of Bryoinformatics: Compiling, Maintaining, and Disseminating a Critical Taxonomic Resource
* John Brinda, Missouri Botanical Garden, United States
John Atwood, Missouri Botanical Garden
In order to precisely identify and communicate information about a plant species, biodiversity researchers must use its scientific name. However, determining the correct application of a scientific name is often a complex process that involves not only the name itself, but also how it relates to the many thousands of other published names. Two massive bibliographic works form the foundation of our current knowledge regarding the nomenclature of bryophytes, namely Index Muscorum and Index Hepaticarum. In more recent years these data have been updated, digitized and spread across the internet, but all of these copies are slowly becoming more and more outdated. It has become clear that a new initiative is needed, one that not only keeps the data current but also makes it more accessible to researchers who require it. Our experience as editors of bryophyte nomenclatural data in Tropicos has shown us that there is demand for a complete list of accepted names (with synonymy) that is well curated and updated regularly. To this end, we have built a website that summarizes the nomenclatural and bibliographic data in Tropicos and presents them as comprehensive list of accepted bryophyte taxa. We would like this site to serve as the focal point for a renewed effort to maintain these data as an authoritative community resource. We feel that this list ought to reflect as much as possible the consensus opinion of experts that are most familiar with the taxa in question and encourage them to get involved in the process.
The fossil record of haplolepideous mosses and its potential for time-calibrating phylogenies
* Alexander Bippus, Oregon State University, United States
Background: The moss fossil record is notoriously limited, with most fossils known from relatively recent Cenozoic deposits. Pre-Cenozoic moss fossils primarily consist of coalified compressions, which typically do not preserve anatomical details that are required for identification at even broad taxonomic levels. However, recent advances in bryophyte paleontology have significantly expanded the number of moss fossils that can be assigned to extant families. Objectives: The objectives of the present study are to: 1) conduct a comprehensive review the fossil record of haplolepideous mosses (Subclass Dicranidae) in order to identify fossils that may be used to time-calibrate phylogenies, and 2) to present a summary of these results for phylogeneticists. Methods: A database of haplolepideous moss fossils was compiled from a comprehensive literature survey. Using this database, fossils assignable to clades within Subclass Dicranidae were identified. Results: The oldest haplolepideous mosses are gametophytes from the Early Cretaceous of Canada that can be assigned to the families Leucobryaceae and Grimmiaceae. Fossils assignable to extant genera in the families Dicranaceae and Rhabdoweisiaceae are found by the Late Cretaceous. The Eocene Baltic and Rovno ambers preserve additional diversity, including six extant genera assignable to four families (Leucobryaceae, Grimmiaceae, Rhabdoweisiaceae, Rhachitheciaceae) as well as the oldest reports of extant species of Dicranidae. Five extant genera assignable to five families (Calymperaceae, Leucobryaceae, Octoblepharaceae, Pottiaceae, Rhachitheciaceae) are also known from Miocene Dominican Amber. Conclusion: Paleontological data document the diversification of Dicranidae since the Early Cretaceous, and provide minimum-age constraints for extant families, genera, and species of haplolepideous mosses.
Recent advances in Dicranidae phylogenetics
* Marina Bonfim Santos, Naturalis Biodiversity Center, Netherlands
Michael Stech, Naturalis Biodiversity Center
Vladimir Fedosov, Lomonosov Moscow State University
The increasing availability of phylogenetic methods has been a fundamental contribution to the study of the haplolepideous mosses, the second largest moss lineage with 4000 species and a range of gametophytic and sporophytic traits. Our goal with this work was to summarize the latest studies and our own results, and thus set the stage for new research. Our analyses were based on mitochondrial and chloroplast markers of specimens representing 37 of the 38 haplolepideous moss families. Phylogenetic reconstructions have shown that the Dicranidae tree comprises a basal grade of early diverging lineages, the proto-haplolepideous mosses, and a derived clade, the core haplolepideous mosses. Their relationships are not in line with the traditional ordinal classification and historically recognized main haplolepideous peristome types. Many lineages were newly recognized, especially within the proto-haplolepideous grade. Part of this newly recognized phylogenetic diversity was identified within weakly morphologically circumscribed taxa shown to be highly polyphyletic, e.g. Ditrichaceae s.l. and Dicranella s.l. In some cases, the morphology of overlooked gametophytic characters, e.g. rhizoidal tubers, appears to be informative of the relationships, however some lineages still lack known diagnostic morphological characters. In other cases, remarkable morphological patterns were confirmed not to correspond to monophyletic groups, e.g., the leucobryoid leaf. Changes to the classification are required in all taxonomic levels to better describe the new findings on the evolutionary relationships, some of which were already formally proposed. Additionally, phylogenetic analyses also indicate many more haplolepideous moss taxa which demand further studies
Peristome anatomy and ontogeny studies advance the understanding of evolution within the haplolepideous mosses
* Mathilde Ruche, Conservatory and Botanical Garden of the City of Geneva - University of Geneva , France
Fred Stauffer, Conservatory and Botanical Garden of the City of Geneva - University of Geneva
Michelle Price, Conservatory and Botanical Garden of the City of Geneva - University of Geneva
The structural complexity of the peristome makes it a powerful feature for unraveling evolutionary events across mosses. In the monophyletic Dicranidae, peristome architecture has been found to hold informative signals across the group, with 13 species from the Dicranales, Grimmiales and Pottiales having been examined so far. The newly developed Technovit 7100® protocol for microtome sectioning of the sporophyte allows for a thorough histological investigation of the peristome, in its entirety and at different stages of development, using 3μm stained sections. Anatomical features observed in longitudinal serially sectioned slices of the peristome and morphological features of the external surfaces of the structure observed using SEM techniques are combined for a global comparison of peristomes in this group of mosses. The observations of peristome features in 13 species from 8 families in the Dicranales, Grimmiales and Pottiales will be presented and discussed, in a phylogenetic context.
Dicranidae in North Asia: cryptic species, clear species and higher level lineages unknown so far
* Vladimir Fedosov, M.V.Lomonosov Moscow State University, Russian Federation
Alina Fedorova, Tsitsin Main Botanical Garden, Russian Academy of Sciences
Recent integrative taxonomic revision of the Rhabdoweisiaceae (Fedosov et al., 2021), although mainly dealt with the circumscriptions of the genera, suggested need in attention to the species level taxonomy. Early diverged lineages like Rhabdoweisia and Dicranoweisia demonstrate high support for geographically isolated infraspecific groupings, so far believed to represent the same species. Results, obtained in the genera Blindiadelphus, Bryoxiphium, Dicranum, Didymodon, Fissidens, Glyphomitrium, Grimmia, Schistidium, Scouleria suggest presence of numerous previously unrecognized species in Asia. Moreover although rather sparse and not specially focussed, our sampling managed to revealed presence of cryptic (or semicryptic) species in Amphidium, Arctoa, Cynodontium, Symblepharis, etc. High morphological and molecular variability revealed within Blindia acuta and several species of Ditrichum might reflect need of circumstantial species level taxonomic studies. Along with diversity, uncovered by phylogenetic studies, several bright records sound solely due to their remarkable morphology. In particular, complete description of sporophytes of “Dicranella” cf. staphylina will appear soon based on extensive specimens collected in Subarctic Siberia, the area where occurrence of this species can hardly be expected. Several previously unknown lineages of Aongstroemiaceae, and Ditrichaceae s.l. also wait to be addressed in the close future in course of Moss flora of Russia project. Our work was supported by RSF grant # 18-14-00121.
Elucidating the phylogeographic history and post-glacial demographic signatures of the moss Racomitrium lanuginosum Brid
* Dennis Alejandro Escolástico-Ortiz, Département de Biologie, Université Laval, Québec, Canada, Canada
Lars Hedenäs, Department of Botany, Swedish Museum of Natural History, Stockholm, Sweden
Dietmar Quandt, Nees Institute for Biodiversity of Plants, University of Bonn, Bonn, Germany
Doerte Harpke, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
Juan Larraín, Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
Michael Stech, Naturalis Biodiversity Center, Section National Herbarium of the Netherlands, Leiden University, Leiden, The Netherlands
Juan Carlos Villarreal, Département de Biologie, Université Laval, Québec, Canada
The evolutionary history of plants in the Northern Hemisphere has been greatly influenced by the climatic oscillations of the Quaternary, mainly the Last Glacial Maximum (LGM). The moss Racomitrium lanuginosum is widely distributed in this region covering arctic, subarctic, and alpine environments. The study aims are to resolve the phylogeographic structure of this species, evaluate the genetic diversity and infer the impact of the LGM in the species distribution range. First, we used the ITS region to resolve the deep relationships and estimate the divergence times using maximum likelihood and Bayesian analyses. Then, we applied the genotyping-by-sequencing (GBS) method to infer the phylogeographic structure and migration events among genetic groups using single nucleotide polymorphisms (SNP). Finally, we obtained species records to conduct species distribution models in the present time, the LGM (22Kya), and the Last Interglacial period (110Kya). Phylogenetic analyses based on ITS indicate the presence of three well-differentiated clades suggesting cryptic speciation. Molecular dating indicates that R. lanuginosum originated during the Pliocene (~5.3Mya). Genetic structure based on SNP’s revealed four groups dispersed across Alaska, Canada, Greenland, and Scandinavia with active migration between them. Species distribution models indicate a reduction in the distribution area of R. lanuginosum during the LGM followed by post-glacial expansion. We hypothesize that one group of Alaskan samples represents refugial populations of the LGM. The phylogeography of R. lanuginosum was shaped by incomplete lineage sorting, admixture, and cryptic speciation. These events highlight the complex demographic history that plants experienced in sub-arctic and arctic regions.