Integrative taxonomy of an East Asian songbird indicates rapid dwarfism after island colonization

A new study on the Japanese and Manchurian Bush Warbler (Horornis diphone–canturians) species complex reveals rapid evolutionary changes, including dwarfism and vocal divergence, following colonization of the remote Ogasawara Islands approximately 200,000 years ago. Using multi-locus phylogeographic and acoustic analyses, researchers confirmed that two continental subspecies (borealis and canturians) belong to H. canturians, contrary to recent proposals. While the endemic subspecies H. d. diphone shows distinct phenotypic traits, its lack of reciprocal monophyly and recent divergence time suggest retaining its current subspecies status. The study also highlights reduced genetic diversity in H. d. diphone, emphasizing the need for conservation efforts in the Ogasawara Islands to protect this unique subspecies.

Wei, C., Peng, L., Zhang, Y., Nishiumi, I., Carey, G. J., Liu, Z., Alström, P., Dong, L., & Liu, Y. (2024). Integrative taxonomy of an East Asian songbird indicates rapid dwarfism after island colonization. Zoologica Scripta, 53(5), 509–522. Portico. https://doi.org/10.1111/zsc.12675