Resolving neutral and deterministic contributions to genomic structure in Syntrichia ruralis (Bryophyta, Pottiaceae) informs propagule sourcing for dryland restoration

Syntrichia ruralis is a cosmopolitan moss that occupies steep environmental gradients. In arid to semi-arid regions of the world it is a key component of biological soil crusts, which are fundamental to healthy dryland ecosystem processes. As such, S. ruralis has attracted the attention of conservationists seeking to restore degraded biological soil crust communities and their associated vascular flora. Here, we generate genomic data for S. ruralis populations that span climatic gradients across the Colorado Plateau of the southwestern USA to investigate the contributions of neutral and deterministic processes to the partitioning of genomic structure. Although S. ruralis appears to be highly dispersible, geographic proximity significantly predicts genomic similarity. In addition, even when taking into account apparently high migration rates among populations and spatial autocorrelation of allele frequencies, some genomic variation is explained by environmental gradients correlated with elevation and latitude. Consequently, efforts to restore dryland ecosystems by establishing S. ruralis as a foundation should include strategies to ensure that propagule sources of this moss are environmentally stratified and targeted to the current/future climates of restoration sites.

砂生银藓（Syntrichia ruralis）是一类广布全球的藓类植物，栖息于陡峭的环境梯度中。在全球干旱至半干旱区域，它是生物土壤结皮（biological soil crusts）的核心组成部分，而生物土壤结皮对于维持健康的旱地生态系统过程至关重要。正因如此，砂生银藓引起了保护生物学家的关注——这些学者致力于修复退化的生物土壤结皮群落及其伴生维管植物。本研究针对横跨美国西南部科罗拉多高原气候梯度的砂生银藓种群生成基因组数据，以探究中性过程与确定性过程对基因组结构分化的贡献。尽管砂生银藓看似具备极强的传播能力，但地理邻接程度可显著预测其基因组相似性。此外，即便考虑到种群间看似较高的迁移率以及等位基因频率的空间自相关，仍有部分基因组变异可由与海拔和纬度相关的环境梯度所解释。因此，通过定植砂生银藓作为建群物种来修复旱地生态系统的工作，应配套相关策略，确保该藓类的繁殖体来源按环境梯度分层，并适配修复位点当前及未来的气候条件。