小笠原諸島で樹上性外来トカゲの痕跡を探る―葉面環境DNAのふき取りで高感度に侵入検知―

2026-05-21 京都大学

京都大学、自然環境研究センター、環境省などの研究グループは、小笠原諸島に侵入した特定外来生物グリーンアノールを、葉面に残された環境DNA(eDNA)のふき取りによって高感度に検出する新手法を開発した。樹上性トカゲは目視や捕獲が難しく、従来の粘着トラップでも低密度地域では検出が困難だったが、本研究では葉表面から採取したDNAを解析することで、超低密度生息地でもグリーンアノール由来DNAを検出することに成功した。葉面には樹上生物の痕跡DNAが残ることから、本手法は他の樹上性爬虫類や昆虫、希少種調査にも応用可能と期待される。外来種の分布拡大を早期に把握できるため、生態系保全や侵略的外来種管理への貢献が期待される。研究成果はBiological Invasions誌に掲載された。

小笠原諸島で樹上性外来トカゲの痕跡を探る―葉面環境DNAのふき取りで高感度に侵入検知―
研究成果の概要。特定外来生物であるグリーンアノールの生息を、葉上に残された環境DNAを分析することで検知する手法の開発に成功した。(©辻冴月)

<関連情報>

樹上性の外来爬虫類を検出するための陸上環境 DNA サンプリング手法の開発:小笠原諸島のグリーンアノールにおける事例研究 Developing terrestrial environmental DNA sampling methods for detecting arboreal invasive reptiles: a case study of the green anole in the Ogasawara Island, Japan

Satsuki Tsuji,Yuki Murakami,Mitsuhiko Toda,Yosuke Yagami,Kou Ashizawa,Takuro Nishiwaki & Nayuta Yamamoto
Biological Invasions  Published:21 March 2026
DOI:https://doi.org/10.1007/s10530-026-03797-4

Abstract

Early detection of invasive alien species is essential for preventing establishment and mitigating ecological impacts, particularly in island ecosystems harbouring evolutionarily isolated endemic species. Recently, despite increasing reptile introductions and their suggested widespread impacts, methods for monitoring arboreal invasive reptiles remain limited. This study addressed the need for practical detection tools by developing terrestrial environmental DNA (eDNA) sampling methods that collect DNA from leaf surfaces to detect the arboreal invasive green anole (Anolis carolinensis) in the Ogasawara Islands, Japan. Two methods, wiping leaf surfaces with gauze and rinsing with sprayed water, were tested. At an invaded site, green anoles were successfully detected in eight out of 10 samples in both methods. Although no significant difference in eDNA concentration was observed, the wiping method was selected for its greater simplicity. Subsequently, the relationship between green anole population density and eDNA concentrations detected using the wiping method showed a significant positive correlation, suggesting the potential of terrestrial eDNA to reflect arboreal reptile abundance for quantitative biodiversity assessments. Furthermore, the successful detection of eDNA even in the extremely low-density habitat of the green anole demonstrates the usefulness of eDNA-based surveys for early detection of invasions. The method developed here may be broadly applicable to terrestrial biodiversity monitoring, especially in tree-dwelling taxa. Given accelerating biological invasions and biodiversity loss, this approach is expected to benefit managers, conservationists, and researchers concerned with terrestrial ecosystems.

1903自然環境保全
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