Improving phylogenetic resolution of the Lamiales using the complete plastome sequences of six Penstemon species

Abstract

The North American endemic genus Penstemon (Mitchell) has a recent geologic origin of ca. 3.6 million years ago (MYA) during the Pliocene/Pleistocene transition and has undergone a rapid adaptive evolutionary radiation with ca. 285 species of perennial forbs and sub-shrubs. Penstemon is divided into six subgenera occupying all North American habitats including the Arctic tundra, Central American tropical forests, alpine meadows, arid deserts, and temperate grasslands. Due to the rapid rate of diversification and speciation, previous phylogenetic studies using individual and concatenated chloroplast sequences have failed to resolve many polytomic clades. We investigated the efficacy of utilizing the plastid genomes (plastomes) of 29 species in the Lamiales order, including five newly sequenced Penstemon plastomes, for analyzing phylogenetic relationships and resolving problematic clades. We compared whole-plastome based phylogenies to phylogenies based on individual gene sequences (matK, ndhF, psaA, psbA, rbcL, rpoC2, and rps2) and concatenated sequences. We also We found that our whole-plastome based phylogeny had higher nodal support than all other phylogenies, which suggests that it provides greater accuracy in describing the hierarchal relationships among taxa as compared to other methods. We found that the genus Penstemon forms a monophyletic clade sister to, but separate from, the Old World taxa of the Plantaginaceae family included in our study. Our whole-plastome based phylogeny also supports the rearrangement of the Scrophulariaceae family and improves resolution of major clades and genera of the Lamiales.

Characterization of the plastome of Physalis cordata and comparative analysis of eight species of Physalis sensu stricto

“…Boundary variations are heritable and provide information on evolutionary and speciation processes. These mutations can be traced throughout the evolutionary process and used as evidence of shared ancestry ( Stettler et al 2021 ). In the Physalis species analyzed here there appears to be no evolutionary pattern that characterizes the boundaries of the four regions; future studies are necessary to identify a particular pattern in the genus.…”

Whole-genome sequence and annotation of Penstemon davidsonii

“…In addition to several chloroplast genomes ( Ricks et al . 2017 , Stettler et al . 2021 ), 2 nuclear genomes have recently become available for Penstemon, P. barbatus ( Wessinger et al .…”