Morphological and genetic discrepancies in populations of Oreocarya paradoxa and O. revealii: the impact of edaphic selection on recent diversification in the Colorado Plateau

PREMISE OF THE STUDY: Investigations of recently derived and edaphically (soil) defined plant systems have provided insight into important mechanisms of ecological divergence. We investigated the impact of edaphic adaptation on recent divergence between two Colorado Plateau endemics: the gypsum facultative Oreocarya revealii (Boraginaceae) and its more generalist sister species O. paradoxa. We assessed morphological stability, genetic identity, and soil chemistry to determine whether O. revealii is a distinct lineage edaphically adapted from O. paradoxa, as has been described in the literature. METHODS: We genotyped 21 populations throughout the ranges of both species using 11 microsatellite markers and three plastid regions (trnL-F, trnT-L, trnQ-rps16) for haplotype analysis. We compared these data with soil chemistry (Ca and S concentrations, indicating gypsum levels), location, and morphological identity of populations. KEY RESULTS: Soil chemistry failed to explain genetic or morphol...