進化の変化を示す家系網モデル(Family Webs May Capture Evolutionary Change Better Than Family Trees)

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2025-08-22 ノースカロライナ州立大学(NCState)

NC StateのGeorge Tiley教授らは、生物の進化関係を「家系樹(family tree)」ではなく「網(family web)」として表現する方が適切だと提案した。従来の系統樹はシンプルで扱いやすい一方、全ゲノム解析の進展により、種間交雑や遺伝子流動といった**網状進化(reticulate evolution)**が無視できないことが判明している。研究チームは、これら複雑な関係を表現できる「系統ネットワーク」の有用性を強調した。進化史を樹木のように単線的に描くのではなく、網として表現することで、説明困難な不確実性を解消できる可能性がある。また、このアプローチは生物多様性保全にも応用可能であり、限られた地域にしか存在しない微細固有種が、独立した系統か交雑起源なのかを区別する判断基盤となり、保全政策の優先順位付けにも役立つ。成果は進化研究と保全科学の双方に新たな視点をもたらす。

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系統ネットワークが生物多様性研究を強化する Phylogenetic networks empower biodiversity research

Sungsik Kong, Claudia Solís-Lemus, and George P. Tiley
Proceedings of the National Academy of Sciences  Published:July 28, 2025
DOI:https://doi.org/10.1073/pnas.2410934122

進化の変化を示す家系網モデル(Family Webs May Capture Evolutionary Change Better Than Family Trees)

Abstract

Reticulate evolution has long been recognized as a key mechanism that contributes to genetic and trait diversity. With the widespread availability of genomic data, investigating historical reticulate evolution across taxa has gained significant attention, driven by the rapid development of statistical methods for detecting nontreelike patterns. Phylogenetic networks provide a biologically intuitive approach to depicting evolutionary processes such as hybrid speciation and introgressive hybridization, which result in signatures of historical gene flow. Interpreting phylogenetic networks is especially critical for groups of conservation concern that lack reference genome resources and explicit hypotheses from prior investigation, such as those based on molecular data, morphology, or species distributions. Here, we highlight recent advances in computational methods for inferring networks from genome-scale data and offer guidelines for deriving biological insights from phylogenetic networks. Particular emphasis is placed on modeling hybridization and whole-genome duplication in the context of allopolyploidization. Practical recommendations for empirical studies and the limitations of commonly used methods are discussed throughout. We anticipate that phylogenetic networks will influence conservation biology and biodiversity research, emphasizing the need for careful consideration of reticulate evolution inferred from these networks in the near future. Networks will accelerate other pressing avenues of biodiversity research, especially investigations of orphan crops and climate change resilience in natural systems. The promise of phylogenetic networks connects with broader themes in the special feature Monitoring and restoring gene flow in the increasingly fragmented ecosystems of the Anthropocene by providing an emerging probabilistic framework for inferring historical connectivity between species and populations.

細胞遺伝子工学
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