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Press Releases

DATE2024.07.18 #Press Releases

Overlooked Extinction Risks of World Natural Heritage Ogasawara Endemic Species

--Assessment based on genomic vulnerability--

Summary

There are about 100 species of the genus Noton known in Asia and Oceania, and they are used for ornamental and medicinal purposes. Four taxonomic groups are distributed in Japan, but three of these (Munin nobotan, Hahajima nobotan, and Iou nobotan) are endemic to the Ogasawara Islands, a World Natural Heritage site, and are all rare. Of these, the population of the Munin nobotan has been small since its discovery, and the Ministry of the Environment has implemented intensive conservation measures, including a protection and propagation project, but no such measures have been taken for the Hahajima nobotan and the Iou nobotan. A group led by Professor Yuji Isagi and Researcher Yukihiro Kobayashi of the Graduate School of Agriculture, Kyoto University, together with Technical Specialist Yoshiteru Komaki of the Koishikawa Botanical Garden, School of Science, The University of Tokyo, conducted a comparative genome analysis of Munin nobotan, Hahajima nobotan, and Iou nobotan, as well as common species of nobotan, and found that all the Ogasawara endemic taxa have higher genetic diversity than common species of nobotan. The results of comparative genome analysis showed that all of the Ogasawara endemic taxa had lower genetic diversity than the common species of nobotan. In particular, the Hahajima nobotan has an extremely fragile genome structure, with a high rate of detrimental amino acid mutations and almost all genetic differences within and among individuals have been lost. The results of this study will provide useful information for understanding the origin of the biodiversity and unique ecosystem of the Ogasawara Islands, and for developing efficient conservation measures with limited resources before the conservation status of endemic species becomes critical.

The study was published online in the international journal Scientific Reports on July 17, 2024.

Figure:Four taxonomic groups of the genus Novotinum growing in Japan
The genomic status of each of the three Ogasawara endemic taxa differed greatly (map based on data from the Ministry of Land, Infrastructure, Transport and Tourism's National Land Data Download Site https://nlftp.mlit.go.jp/ksj/gml/datalist/KsjTmplt-N03-2024.html).

For more information, please visit the website of Kyoto University.(in Japanese)

Journal

Journal name
Scientific Reports
Title of paper