Collaborative Research: Dimensions: Desiccation and Diversity in Dryland Mosses

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Mosses are the second most diverse group of land plants and they play important ecological roles in terrestrial ecosystems. Since an early divergence from other land plants some 450 million years ago, mosses took a different path than vascular plants to solving the challenges to survival and reproduction posed by terrestrial environments. One important trait that is well developed in mosses is the capability of drying without dying, known as desiccation tolerance (DT). This critical trait allows many mosses to survive and reproduce even in drylands, and may be the key to their survival in the face of current, rapid climate change. Syntrichia is a large and diverse genus of mosses occurring worldwide and generally in dryland habitats. Despite their dominance in certain communities such as biological soil crusts, surprisingly little is known about the drivers of biodiversity in this clade. This interdisciplinary project integrates research from genomic, organismal, population, and community levels of organization in order to build a robust understanding of past and present dimensions of biodiversity in Syntrichia. The overall goals are to understand the evolutionary and ecological mechanisms that have produced and maintained functional diversity at these different levels of organization, and promote training, teaching, and learning via: (1) formal education through field and laboratory research; (2) informal education involving a classroom module, short-film series featuring mosses and biocrusts transitioning from desiccation dormancy, a citizen science program "Citizens of the Crust," and a series of free public workshops.The research will examine tradeoffs between asexual and sexual reproduction, and between phenotypic plasticity and canalization into specialized genotypes, by examining the mechanisms underlying traits (including phenotypic plasticity) that drive diversification, reproduction, habitat selection, and physiological trait evolution in environments with varying degrees of water stress. Specific methods to be employed include: (1) sequencing the full genomes of S. caninervis and S. ruralis; (2) using next generation sequencing (NGS) to develop genotypic markers for population-level genetic variation studies, signature transcriptome tools for phenotypic analyses (related to ecophysiological and ecosystem investigations), and multiple single-copy genes for phylogenetic analysis; (3) transcriptomics experiments comparing different development stages and sexes of both species in response to desiccation stress and reproductive state; (3) ecophysiological experiments on multiple populations of S. caninervis and S. ruralis, and all 15 species of N. American Syntrichia, to assess phenotypic plasticity in the key trait of DT; (5) population genetic studies of S. caninervis and S. ruralis in different environments; (6) building a robust phylogeny for Syntrichia and using it to understand evolutionary trends and correlations among the traits under study, as well as to produce a refined classification; (7) examining the role of genetic, functional, and phylogenetic diversity in the resilience to climate change of biocrust communities that are dominated by Syntrichia (with co-occurring mosses, lichens, and cyanobacteria) in field and greenhouse experiments.