Overview
- The PNAS Nexus study by Takema Saitoh and colleagues formally describes Phylloscopus tokaraensis as distinct from Ijima’s Leaf Warbler.
- Genome-wide and mitochondrial analyses reveal a deep split with no detected gene flow, and recordings show consistent differences in song.
- The two lineages are estimated to have diverged about 2.8–3.2 million years ago.
- Breeding of the Tokara leaf warbler is confirmed on Nakanoshima with very small, isolated populations across the Tokara Islands.
- Both lineages have very low genetic diversity and signs of past declines; the authors note threats such as introduced weasels, goat-driven habitat change, and volcanic risk, recommend monitoring, and call for the Tokara species to be assessed as Vulnerable while Ijima’s is already listed as such.