Spatial genetic structuring in a widespread wetland plant on a plateau: Effects of elevation‐driven geographic isolation and environmental heterogeneity

Abstract Highlands are ideal research areas for improving our understanding of the influence of ecological factors on the diversity and spatial patterns of natural species. Elevation‐driven physical and environmental isolation greatly affect the evolution of plants. The mechanisms and essential drivers underlying these processes may differ among research scales, habitats and landscapes. Wetlands are important elements of the Qinghai–Tibetan Plateau, which is the highest plateau in the world, and these habitats harbour high aquatic organismal diversity. However, how the environments shape the genetic variation and structure of hydrophilous plants is poorly understood. Using microsatellite markers and a chloroplast fragment, we quantified the genetic diversity and spatial genetic pattern of Stuckenia filiformis , one of the most widespread aquatic plants on the plateau. The relative contributions of geography, climate and local conditions to intra‐ and interpopulation variation were estimated. The results showed that intrapopulation genetic variation of the plant is moderate to high and not constrained by high‐altitude environments. Topographical isolation mainly contributes to the genetic structure of S. filiformis , as inferred by simple sequence repeats and chloroplast DNA data. Significant effects of environmental variables on the spatial genetic patterns of this freshwater species were also suggested by landscape genetic analysis. Infrequent long‐distance dispersal, sexual recruitment and annual growth are probably important for the maintenance and distribution of this variation. Our findings imply a combined effect of geography and elevation‐driven environmental heterogeneity on the evolution of aquatic organisms in highlands.