This proposal funds research on the taxonomy and diversification of the moss genus Sphagnum, also known as peat mosses. The research focuses on a lineage of peat mosses that occur primarily in the "Pacific Rim" region from California north to Alaska and south to Japan and China, and includes about 15-20 species. The work uses data from DNA sequences and highly variable microsatellite genes to determine how many species there are and how to tell them apart. A series of hypotheses are to be addressed, clarifying exactly where individual species grow, how the plants reproduce, and the frequency and efficacy of sexual and asexual reproduction. One outcome will be a thorough taxonomic treatment for the Pacific Rim species of Sphagnum, with illustrations and other resources to permit accurate identifications of species. The proposal also funds workshops on identification of Sphagnum species, targeting wetland ecologists doing vegetation surveys and amateur scientists, many of whom work for environmental NGOs.
Sphagnum-dominated peatlands have profound effects on global climate, regional hydrology, and the occurrence of many other organisms, plant, animal, and microbial. Ecosystem function (productivity, decomposition, movement of minerals and nutrients) is determined by the suite of species that occur there, and recent biogeochemical studies indicate that different Sphagnum species have significantly different chemistries and other properties that affect peatland function. For that reason, clear species circumscriptions are critical to understanding their ecological impacts. This research uses modern molecular approaches, coupled with field and specimen-based research, to provide a sound taxonomic treatment essential for evaluating the role of peat mosses in the global biosphere.
The world's biodiversity both shapes and is shaped by current and past climates. This project focused on a group of ecologically critical mosses -- peatmosses (the genus Sphagnum) -- that occur around the margins of the Pacific basin from California northward to Alaska and adjacent Siberia, and southward to Japan and China. Peatmosses are important determinants of global climate because they store huge amounts of carbon (peat) that accumulates as the plants grow. There are hundreds of species of peatmoss and many of them differ in traits that impact how they grow and store carbon, so understanding peatmoss diversity has profound implications for ecology and therefore human welfare. Mosses reproduce and spread via tiny spores rather than seeds and as a result, many have very broad geographic ranges. This project clarified how many species of peatmoss are in this particular group (16), what their geographic ranges are in the Pacific Rim region, how often they have been able to spread between continents, and how the species differ from one another ecologically. This project also provided new insights into the structure of the peatmoss genome. Molecular analyses clarfied what genes are expressed in living plants, and demonstrated that during the diversification of peatmosses, their entire genome has been duplicated. It is well known that whole genome duplications of this sort have been important in the adaptation of many organisms to their environments, and our molecular work holds promise for a better understanding of peatmoss ecology and its relationship to genome structure. Partly motivated by this project, the Joint Genome Institute (part of the Department of Energy, DOE) has approved a proposal to sequence the entire genome of a representative species of peatmoss.
