About Natural World Heritage

Values of the Ogasawara Islands

On the Ogasawara Islands, unique speciation has occurred in a limited area resulting in the appearance of many endemic species, and the ongoing evolutionary processes can be seen particularly in land snails and plants.One hundred species of land snails have been confirmed, and among those, 94% are endemic. Moreover, new species are still being discovered. In the genus Mandarina, the color and shape of the shells differ depending on the habitat environment such as arboreal and terrestrial

Biodiversity of the genus Mandarina (Courtesy of Satoshi Chiba)
Color variations of Mandarina sp. A 

Dry shrub forests are composed of endemic species similar to those of laurel forests in Southeast Asia and Okinawa. It is thought that the forest was established by the constituent species of the laurel forest adapting to the climatic conditions after reaching the oceanic islands of Ogasawara. However, there are no oaks dominated in the continents, and the species composition is unique.

In addition, many endemic species derived from adaptive radiation can be seen, while the unique evolutionary patterns of oceanic islands, such as sex differentiation and woodiness formation of herbaceous plants, can also be observed.

Thus, the Ogasawara Islands are a “laboratory of evolution” preserving processes of the speciation on the oceanic islands and are said to be a remarkable example of an important ongoing biological process. This is how the unique ecosystem of the Ogasawara Islands was formed.

Dry shrub forest of Anijima Island