Research press release



マンモスステップ(独特な植生群落と野生動物群集の中でマンモスが生息していた環境)は、現代のどの生態系とも異なるユニークな生態系だったことを明らかにした論文が、Nature に掲載される。この研究は、広範な環境DNA解析に基づいており、過去5万年間にマンモスステップに生じた変化を説明するために役立ち、象徴的なマンモスの絶滅を含む大型動物相の消滅の時期と原因を解明する手掛かりになる。


今回、Eske Willerslevたちは、マンモスステップの構成を十分に理解するため、北極の535地点で採取された過去5万年間にわたる古代の動植物のものとされる環境DNAのサンプルを調べるとともに、北極の現生植物種(1500種以上)のDNAも解析して参照情報資源とした。Willerslevたちの見解では、マンモスステップは寒冷で乾燥した地域的に複雑なステップで、草、スゲ、被子植物、低木が生育していたと考えられ、2つの有力説の中間のどこかに位置付けられるものだったとされる。


The Mammoth Steppe, the environment in which mammoths lived among a distinct community of vegetation and wildlife, was a unique ecosystem unlike anything that exists today, research in Nature reveals. The study, which draws on extensive environmental DNA analyses, helps to explain how this ecosystem changed over the past 50,000 years, and sheds light on the timing and cause of megafaunal extinctions, including the demise of the iconic woolly mammoth.

There has been some debate about what the Arctic ecosystem was like during the heyday of the Mammoth Steppe, in the later stages of the Pleistocene epoch (around 50,000 years ago), with two prevailing theories. Some studies propose that it was an extensive grassland populated year-round by grazers, such as woolly mammoth and bison, whereas others suggest that it was a more diverse ecosystem, including steppe and tundra, and an accompanying mix of animal life that was regionally and temporally diverse.

To fully understand the make-up of the Mammoth Steppe, Eske Willerslev and colleagues studied samples of environmental DNA, belonging to ancient plants and animals, from 535 different Arctic sites that span the past 50,000 years. They also analysed the DNA of more than 1,500 contemporary Arctic plant species as reference sources. The Mammoth Steppe was somewhere in between the two prevailing theories, the researchers suggest. It was a cold, dry and regionally complex steppe, composed of grasses, sedges, flowering plants and shrubs.

Some animal species survived much later than had previously been thought, the study also reveals. There is evidence in mainland Siberia for the presence of the woolly mammoth 3,900 years ago, woolly rhinoceros at 9,800 years ago and bison 6,400 years ago. This finding implies that humans coexisted with these megafaunal species for tens of thousands of years, and that human hunting was not an important factor in their demise. Instead, extinction came when the last pockets of steppe–tundra vegetation gave way to peatland, as the climate became warmer and wetter.

doi: 10.1038/s41586-021-04016-x

「Nature 関連誌注目のハイライト」は、ネイチャー広報部門が報道関係者向けに作成したリリースを翻訳したものです。より正確かつ詳細な情報が必要な場合には、必ず原著論文をご覧ください。

メールマガジンリストの「Nature 関連誌今週のハイライト」にチェックをいれていただきますと、毎週最新のNature 関連誌のハイライトを皆様にお届けいたします。