Phylogenomic insights into Adenophora and its allies (Campanulaceae): Revisiting generic delimitation and hybridization dynamics.

Abstract

Hybridization and introgression have long obscured relationships within Adenophora and its relatives, complicating generic delimitation. Leveraging deep genome skimming (DGS) data, we generated a large dataset, including thousands of single-copy nuclear (SCN) genes and plastomes, to untangle this reticulate history. Specifically, 9.89 terabytes (TB) of DGS data from 165 samples-representing 48 species and 13 subspecies of Adenophora (out of ca. 72 species) plus 24 outgroup species-yielded 1506 SCN genes and 77 plastid coding sequences. Tree-like phylogenies inferred with both coalescent- and concatenation-based methods revealed pronounced gene tree heterogeneity. Subsequent analysis showed that incomplete lineage sorting contributed minimally to this discordance; instead, hybridization and introgression were the primary drivers of early diversification. Integrating phylogenomic, morphological, and geographic evidence, we propose a revised generic framework for this group. Adenophora is expanded to include Campanula delavayi and the Korean Peninsula endemic genus Hanabusaya. We also recommend reinstating Hyssaria as a distinct Central Asian genus and introducing two new genera, Boreoasia and Rosomala.