Monarda subg. Monarda is a morphologically diverse genus of flowering plants that is endemic to North America.
Systematics: Despite its diversity of floral morphologies, chemical profiles, and pollination schemes, molecular systematics in Monarda subg. Monarda has received little attention. However, several new species have recently been described, other undescribed varieties are known to exist, and gene flow between species seems to be common within the genus, resulting in a confusing assortment of taxonomic treatments. I hope to clarify Monarda subg. Monarda systematics, setting the stage for downstream studies looking at speciation and trait evolution.
I sampled throughout the subgenus, including known species, newly described species, and potentially undescribed varieties. I then used 3RAD, a reduced-representation library preparation technique, for genome-wide sequencing of many samples at low-cost. Finally, I used state-of-the-art species tree and species network estimation methods to resolve the species relationships, many of which are shallow-scale.
Downstream Research
Taxonomy: There are several morphologically distinct varieties of Monarda that are included in the systematics study. Further alpha taxonomic research could be necessary for characterizing these populations.
Reference genome: I hope to assemble a reference genome for Monarda fistulosa using long-read sequencing (e.g. PacBio HiFI) and Hi-C scaffolding.
Hybridization: Present-day hybridization appears to be common among species of Monarda, but molecular studies have not been conducted. Because of this, “species” like Monarda media continue to be recognized. Complex patterns of hybridization have important implications for Monarda systematics, and studying them might help us understand modes of speciation in Monarda. Greenhouse experiments could also offer clues about trait evolution in Monarda and other groups.
Speciation: Monarda diversity appears to be concentrated in the lower Appalachian Mountains and could result from repeated isolation and re-expansion from glacial cycling. However, some species morphologies and distributions appear to indicate past ecological speciation or ongoing reinforcement.