Mechanism of extinction of indigenous species community by the invasion of domestic alien species

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06813
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 45040:Ecology and environment-related
• Research Institution: Mie University
• Principal Investigator: Kawamura Kouichi 三重大学, 生物資源学研究科, 教授 (80372035)
• Co-Investigator(Kenkyū-buntansha): 古丸 明 三重大学, 生物資源学研究科, 教授 (10293804)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 国内外来種 / 遺伝的攪乱 / 種間関係 / 生殖的隔離 / 系統地理 / 種間交雑 / 遺伝子浸透 / 棲み分け

Outline of Final Research Achievements

Genetic and ecological effects of domestic alien species on interspecific relationship of indigenous species were examined, focusing on the relationship of Rhynchocypris lagowskii and R. oxycephala. Molecular　analyses revealed that exotic genome, probably of domestic alien species origin, was detected in populations of the two species in the Ise Bay basin. In one of the populations, with exotic genome introgressed at high frequency, the ratio of hybrid between the two species was high. In this population, not only F1 but also BC were observed, together with individuals with mismatch between nuclear and mitochondrial genomes. Contrary to females, infertility was suggested in F1 males, likely warranting the persistence of both the species, irrespective of high hybridization. Although introgression of exotic genome was high in hybrids, direct relationship between the genome and hybridization was not detected, with the sigh of effects of man-made habitat change on hybridization.

Free Research Field

分子生態学

Academic Significance and Societal Importance of the Research Achievements

ブラハヤとタカハヤの混生域における交雑個体の比率の高さの理由として、配偶行動における交配前隔離の不在が原因であり、こうした乱婚とも言える状況下で両種の存続を可能としている要因として、交雑個体の雄における不妊の可能性が明らかとなった。DNA分析の結果から調査地点においては両種共に移入の可能性の高い個体が多く見られた事から、交配前隔離の不在は外来個体における交配前隔離の不在の可能性も覗われたが、野外調査の結果から堰堤等の河川構築物による移動阻害が両種の交雑を促進している可能性が高い事が示唆された。これらの結果は、同所的に生息する近縁種の存続においては生態系の連続性が重要性であることを意味している。