Carrot tree populations are older, and more diverse than expected

Newswise – Tsukuba, Japan – It’s often assumed that the island’s collections of flora and fauna are just plain, crunchy cousins ​​to those on the mainland. But now, researchers from Japan have discovered that the islanders may be tougher and more complex than previously thought.

In a recently published study, a research group led by the University of Tsukuba revealed that the inhabitants of the northernmost beech island of Siebold, Vajus Krinataolder and more genetically diverse than expected.

The populations of the islands and the mainland often differ as a result of the islands’ geographic isolation, which is often assumed to limit the genetic diversity of their populations. However, a number of studies of wild plants have shown that islanders have great genetic diversity despite their remoteness, suggesting that the processes behind their diversity are more complex than previously thought.

“Although many island groups have existed for thousands of years or more, the origins of some of them are still unknown,” says Professor Yoshiaki Tsuda, lead author of the study. This includes residents of the northernmost islands of Japan of the native species F. crenata. “

The research group investigated residents F. crenata On Okushiri Island in the Sea of ​​Japan, which is believed to have separated from the mainland in the Middle Pleistocene (Ice Age, which occurred 2.58 million to 11,700 years ago), and has remained separate ever since. This species’ northward spread on the mainland began approximately 6,000 years ago, after the last ice cap (LGM). The researchers studied the genetics of the island’s population and those of neighboring regions, and found that the island’s population had high genetic diversity, and may not have arisen from a single colonization event.

The populations of Okushiri Island had a similar number of special alleles (genetic sequences present in one population and essentially absent in other populations) to the populations studied in nearby Hokkaido, indicating the presence of relict populations on Okushiri Island. A progenitor is a group of organisms that were more widespread or more diverse in the past in a restricted area.

These results, along with studies of paleoecology and vegetation, as well as the geology of the island, point to this F. crenata She persisted in the hidden refuges (places where climate-sensitive species could live regardless of incompatibility with the regional climate) on the island.

“Our evidence indicates that groups of this type already existed on Okushiri Island before LGM, and persisted there for much longer than previously thought,” explains Professor Tsuda. The findings of this study contribute to a growing body of evidence that island plant populations are more genetically diverse than previously estimated, with implications for research and conservation management of island species, and for the study of gene flow between island and mainland populations.

This study was supported by JSPS KAKENHI (JP17K07852 and JP20K06152) and the Core-to-Core Program (Science Platforms Asia and Africa: JPJSCCB20220007) of the Japan Society for the Promotion of Science and the 27th Pro Natura Fund Grant Program of the Pro Natura Japan Foundation.

The original paper

Article titled “The Possibility of a Northern Stability by Zane Siebold,” Vajus Krinataat its northernmost distribution limit on the northernmost island in the Sea of ​​Japan: Okushiri Island, Hokkaido,” published in Frontiers in plant sciences in DOI: 10.3389/fpls.2022.990927


Associate Professor TSUDA Yoshiaki
College of Life and Environmental Sciences, University of Tsukuba

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College of Life and Environmental Sciences
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