Genetic assessment of the introduced rats found on Lord Howe Island post rodent eradication, new invaders or remnant survivors?

Genetic analysis reveals that black rats detected on Lord Howe Island (LHI) after a successful rodent eradication program are likely remnant survivors, not new invaders. Using mitochondrial DNA and microsatellite markers, researchers found that the post-eradication rats shared identical haplotypes with pre-eradication populations, while differing from mainland Australian and other Pacific island rat populations. Microsatellite data further showed that LHI's pre- and post-eradication rat populations were genetically distinct from mainland NSW populations, indicating limited gene flow despite potential dispersal routes. The low genetic diversity in post-eradication rats suggests they descend from a small number of survivors rather than new introductions.

Frankham, G. J., Helgen, K. M., & Eldridge, M. D. B. (2026). Genetic assessment of the introduced rats found on Lord Howe Island post rodent eradication, new invaders or remnant survivors? NeoBiota, 105, 25–45. https://doi.org/10.3897/neobiota.105.163728