絶滅速度の低下を確認(Extinction rates have slowed across many plant and animal groups, study shows)

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2025-10-22 アリゾナ大学

アリゾナ大学の生態・進化生物学科による最新研究は、過去500年間における植物・節足動物・陸上脊椎動物の絶滅率が20世紀初頭をピークに低下していることを示した。従来「第6の大量絶滅」が進行中とされたが、その予測は過去の島嶼での外来種被害を基にした推定に依存しており、現在の主因である生息地破壊や気候変動とは異なる要因によることが明らかとなった。912種の絶滅記録と約200万種のデータを解析した結果、絶滅は陸上より島で多く、特に貝類や脊椎動物で顕著だった。一方、植物や節足動物では近年絶滅率が低下。気候変動による直接的絶滅の証拠は過去200年では確認されなかった。研究者は「現在の脅威は過去と異なり、保全投資が実際に効果を上げている」と指摘。絶滅速度の鈍化は人間の保全努力の成果であり、危機を誇張するよりも科学的根拠に基づく対策が必要と結論づけた。

<関連情報>

絶滅危機の解明:近年の植物と動物の絶滅の速度、パターン、原因 Unpacking the extinction crisis: rates, patterns and causes of recent extinctions in plants and animals

Kristen E. Saban and John J. Wiens
Proceedings of the Royal Society B  Published:15 October 2025
DOI:https://doi.org/10.1098/rspb.2025.1717

絶滅速度の低下を確認(Extinction rates have slowed across many plant and animal groups, study shows)

Abstract

Biodiversity loss is one of the greatest challenges facing Earth today. The most direct information on species losses comes from recent extinctions. However, our understanding of these recent, human-related extinctions is incomplete across life, especially their causes and their rates and patterns among clades, across habitats and over time. Furthermore, prominent studies have extrapolated from these extinctions to suggest a current mass extinction event. Such extrapolations assume that recent extinctions predict current extinction risk and are homogeneous among groups, over time and among environments. Here, we analyse rates and patterns of recent extinctions (last 500 years). Surprisingly, past extinctions did not strongly predict current risk among groups. Extinctions varied strongly among groups, and were most frequent among molluscs and some tetrapods, and relatively rare in plants and arthropods. Extinction rates have increased over the last five centuries, but generally declined in the last 100 years. Recent extinctions were predominantly on islands, whereas the majority of non-island extinctions were in freshwater. Island extinctions were most frequently related to invasive species, but habitat loss was the most important cause (and current threat) in continental regions. Overall, we identify the major patterns in recent extinctions but caution against extrapolating them into the future.

生物環境工学
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