新種発見速度が過去最高に達していることを示す研究(New species are now being discovered faster than ever before, study suggests)

2025-12-22 アリゾナ大学

米アリゾナ大学の研究チームは、新種生物の発見速度がこれまで以上に加速していることを示す研究成果を発表した。研究では、過去数世紀にわたる分類学データを分析し、近年になって新種の記載数が顕著に増加している傾向を明らかにした。その背景には、DNA解析など分子系統学の進展、リモートセンシングやデジタル標本データベースの活用、国際的な研究協力の拡大があるとされる。一方で、発見が進む地域や生物群には偏りがあり、昆虫や微小生物、熱帯地域では未記載種が依然として多数存在する可能性が高い。研究者らは、新種発見の加速は生物多様性理解を深める好機である一方、環境破壊や気候変動によって記載前に絶滅する種も多いと警告する。分類学的研究と生物多様性保全を同時に推進する重要性が改めて示された。

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既知の生物多様性の過去と未来:新種の出現率、パターン、予測の経時変化 The past and future of known biodiversity: Rates, patterns, and projections of new species over time

Xin Li, Ding Yang, Liang Wang, and John J. Wiens

Science Advances  Published:5 Dec 2025

DOI:https://doi.org/10.1126/sciadv.adz3071

新種発見速度が過去最高に達していることを示す研究(New species are now being discovered faster than ever before, study suggests)

Abstract

Our understanding of biodiversity patterns comes primarily from described species. Here, we analyze how known biodiversity has increased across living organisms. Past research suggested that the number of new species per year peaked near 1900 and that only ~2 million species exist. We find that overall rates of species descriptions have recently accelerated, with the largest numbers of new species per year all in the past ~20 years (2000 to 2020). The largest groups grew the most quickly during this period, including animals, arthropods, insects, and beetles. However, long-term trends in rates of species descriptions were often unrelated to recent rates and current richness. For example, rates for fungi have recently increased, whereas rates for insects have not. Extrapolating these rates of species descriptions into the future requires considerable caution. Nevertheless, some intriguing patterns are suggested, such as unexpectedly high projected species numbers of plants, fungi, arachnids, malacostracan crustaceans, ray-finned fishes, and amphibians.

地球規模の生物多様性の推定:隠蔽昆虫種の役割 Estimating Global Biodiversity: The Role of Cryptic Insect Species

Xin Li ,John J Wiens

Systematic Biology  Published:27 October 2022

DOI:https://doi.org/10.1093/sysbio/syac069

Abstract

How many species are there on Earth and to what groups do these species belong? These fundamental questions span systematics, ecology, and evolutionary biology. Yet, recent estimates of overall global biodiversity have ranged wildly, from the low millions to the trillions. Insects are a pivotal group for these estimates. Insects make up roughly half of currently described extant species (across all groups), with ~1 million described species. Insect diversity is also crucial because many other taxa have species that may be unique to each insect host species, including bacteria, apicomplexan protists, microsporidian fungi, nematodes, and mites. Several projections of total insect diversity (described and undescribed) have converged on ~6 million species. However, these projections have not incorporated the morphologically cryptic species revealed by molecular data. Here, we estimate the extent of cryptic insect diversity. We perform a systematic review of studies that used explicit species-delimitation methods with multilocus data. We estimate that each morphology-based insect species contains (on average) 3.1 cryptic species. We then use these estimates to project the overall number of species on Earth and their distribution among major groups. Our estimates suggest that overall global biodiversity may range from 563 million to 2.2 billion species. [Biodiversity; cryptic species; insects; species delimitation; species richness.]

1903自然環境保全
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