A test of four candidate barcoding markers for the identification of geographically widespread Chimaphila species (Pyroleae, Ericaceae)

Abstract DNA barcoding has been widely used as a tool for species discrimination in closely related plants and at more coarse taxonomic levels, but there have been few reports of such a tool being applied to taxa in “morphological stasis”. In this study, we test the performance of core barcodes (rbcL and matK) and two additional candidate barcodes [psbA-trnH and nuclear ribosomal internal transcribed spacer (ITS)] for the widely distributed, northern temperate monophyletic genus Chimaphila, which exhibits morphological conservatism. In addition to ITS, slowly evolving rbcL and matK independently demonstrate a high resolving ability among Chimaphila species, indicative of the old age of disjunction. We tentatively attribute morphological stasis in Chimaphila to convergence under similar habitat conditions and complex, stable relationships with surrounding autotrophic trees via common mycorrhizal symbioses.