Phylogenetic origin of dioecious Callicarpa (Lamiaceae) species endemic to the Ogasawara Islands revealed by chloroplast and nuclear whole genome analyses

A comprehensive phylogenomic analysis of three dioecious Callicarpa species endemic to the Ogasawara Islands reveals their evolutionary origins and colonization timeline. Using chloroplast genomes and 86 nuclear single-copy genes, researchers determined that these species diverged from East Asian continental relatives approximately three million years ago, likely through long-distance dispersal during the late Pliocene. The study highlights adaptive radiation and shifts in dioecious sex expression as key evolutionary trends on oceanic islands. Phylogenetic trees based on over 10,000 nuclear genes placed the insular species within an East Asian clade, though discrepancies with chloroplast tree topologies suggest incomplete lineage sorting or hybridization events.

Masuda, K., Setoguchi, H., Nagasawa, K., Setsuko, S., Kubota, S., Satoh, S. S., & Sakaguchi, S. (2025). Phylogenetic origin of dioecious Callicarpa (Lamiaceae) species endemic to the Ogasawara Islands revealed by chloroplast and nuclear whole genome analyses. Molecular Phylogenetics and Evolution, 203, 108234. https://doi.org/10.1016/j.ympev.2024.108234