A Broad Phylogenetic Analysis of Boraginaceae: Implications for the Relationships of <I>Mertensia</I>

Abstract

Abstract The phylogenetic relationships of Mertensia (Boraginaceae), which comprises approximately 45 species in both Asia and North America, have been uncertain, and taxonomists have placed the genus in various tribes of subfamily Boraginoideae, with the most recent placements in Trigonotideae and Cynoglosseae. Our study applies molecular phylogenetic methods to test the monophyly and relationships of Mertensia. We used DNA sequence data from the nuclear ribosomal nrITS region and four cpDNA regions (matK, ndhF, rbcL, trnL-trnF) to examine the placement of Mertensia among a sampling of accessions from approximately 70% of the genera of Boraginaceae s. l. Phylogeny reconstructions using maximum parsimony, maximum likelihood, and Bayesian inference were largely congruent with previous molecular phylogenetic analyses of Boraginaceae that had applied far fewer taxa. We recovered five deep clades that correspond to Boraginaceae subfamilies Boraginoideae, Cordioideae, Heliotropioideae, Hydrophylloideae, and Eh...