ゲノムから探るサワガニの複雑な分布と進化史 “色”だけでは見抜けない集団構造を明らかに

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2025-07-16 摂南大学

摂南大学と和歌山県立自然博物館などの研究グループは、次世代シーケンサーを用いてサワガニのゲノムを解析し、日本列島に広く分布する個体が5つの遺伝的集団に分かれることを明らかにしました。これらの集団は地域ごとの地史的要因によって分化し、島をまたぐ飛び地的な分布を形成。一方、体色タイプと遺伝集団は一致せず、青色型は進化史上独立に2回出現したことが判明しました。本研究はサワガニの分類・系統・分布研究の基盤となる成果です。

ゲノムから探るサワガニの複雑な分布と進化史 “色”だけでは見抜けない集団構造を明らかに「サワガニ」の体色タイプ、一塩基多型(SNPs※1)に基づく遺伝的集団構造の地理的分布の概念図

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ゲノムワイドなSNPsを用いたサワガニ種群の遺伝的集団構造解析 Genetic population structure of Japanese freshwater crab, Geothelphusa dehaani species complex using genome wide SNPs

Taiga Kunishima,Kento Takata,Kanto Nishikawa,Kodai Gibu,Miyuki Nishijima & Akira Iguchi
Scientific Reports  Published:15 July 2025
DOI:https://doi.org/10.1038/s41598-025-08085-0

Abstract

The Japanese freshwater crab Geothelphusa dehaani species complex is distributed widely across the Japanese Archipelago. Despite its suggested high genetic and morphological diversity, key aspects such as nuclear DNA (nuDNA) population structure and relationship between body color patterns and genetic populations remain unclear. To address these gaps, this study analyzed genome-wide single nucleotide polymorphisms (SNPs) in nuDNA and mitochondrial DNA (mtDNA) cytochrome oxidase subunit 1 (COI) markers in samples from Hokkaido to the Tokara Islands, Japan. ADMIXTURE analysis identified five distinct populations with significant geographic boundaries. These populations exhibited unique geographical patterns, spanning across islands and enclave distribution, indicating that G. dehaani populations have been shaped by complex factors, including sea level changes and volcanic activity. Regional body color variations partially aligned with SNP clades. Further, combining body color with collection locality data could help identify the specimen populations. Contrasting patterns between mtDNA and nuDNA suggest historical gene flow and introgression, emphasizing the need for caution when interpreting earlier phylogenetic studies based on combined mtDNA and nuDNA sequences. Our findings provide a foundational baseline for future research into the taxonomy, phylogeny, and population dynamics of the G. dehaani species complex, advancing our understanding of its evolutionary history.

細胞遺伝子工学
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