Phylogenomics and biogeography of North American trechine cave beetles (Coleoptera:Carabidae) inferred from ultraconserved elements.

Cave trechine beetles (Carabidae:Trechini) are members of cave communities globally and important models for understanding the colonization, diversification, and adaptation of cave life. In eastern North America, cave trechines are the most species-rich group of terrestrial troglobionts, comprising 150+ taxa in six genera with no closely related extant surface members. Previous studies have hypothesized that Pleistocene climate change was a major driver of cave colonization and diversification for temperate terrestrial cave fauna in this region. However, our time-calibrated molecular phylogeny resulting from the analysis of ultraconserved element loci for 45 species of this clade supports an alternative hypothesis whereby cave colonization of the surface ancestor likely began in the early Miocene in the Appalachians karst region and dispersed into the Interior Low Plateau in an east-to-west manner beginning 17.0 Ma. Major clades attained their present-day distributions by the early Miocene followed by multiple additional episodes of cave colonization and diversification throughout the Pliocene and Pleistocene. The genera Neaphanops, Darlingtonea, Nelsonites, and Ameroduvalius were nested within the genus Pseudanophthalmus, supporting the hypothesis that these taxa are derived from Pseudanophthalmus. While several morphologically defined species groups of Pseudanophthalmus are monophyletic, others were not recovered, warranting future taxonomic and systematic research.