Genetic evidence reveals how goosegrass colonized a newly formed volcanic island

Scientists have discovered genetic evidence explaining how a grass species called Eleusine indica managed to colonize Nishinoshima, a newly formed volcanic island in the Pacific Ocean. This study, published in the Journal of Plant Research, sheds light on the process of establishing life on such remote and isolated environments.

Nishinoshima emerged from volcanic activity in 1973 and has been continuously growing ever since, but very few plant species have been found to thrive there. In 2019, researchers discovered three plant species, including E. indica, surviving in a small remnant of the island's original land area, which is only 0.5 hectares in size.

The genetic analysis of E. indica samples taken from Nishinoshima, mainland Japan, the Ogasawara Islands, the Ryukyu Islands, and Indonesia revealed that the Nishinoshima population is most closely related to populations from the Ogasawara Islands, Okinawa, and Indonesia. This suggests that the grass likely arrived on the island from tropical regions by being carried there by seabirds, such as the brown booby.

Moreover, the study found that the Nishinoshima population has extremely low genetic diversity, indicating that it probably originated from just one or a few seeds. These findings provide rare insight into the early stages of plant colonization and the development of ecosystems in newly formed volcanic islands. They also emphasize the crucial role that seabirds may play in connecting distant island ecosystems through long-distance seed dispersal.