Repeated genetic and adaptive phenotypic divergence across tidal elevation in a foundation plant species

Microgeographic genetic divergence can create fine-scale trait variation. When such divergence occurs within foundation species, then it might impact community structure and ecosystem function, and cause other cascading ecological effects. We tested for parallel microgeographic trait and genetic divergence in Spartina alterniflora , a foundation species that dominates salt marshes of the US Atlantic and Gulf coasts. Spartina is characterized by tall-form (1-2m) plants at lower tidal elevations and short-form (