Phylogeographic origin of a mayfly unisexual reproduction strains and their rapid expansion across Japan

2015 Fiscal Year Final Research Report

• Project/Area Number: 26650160
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Ecology/Environment
• Research Institution: Shinshu University
• Principal Investigator: TOJO Koji 信州大学, 学術研究院理学系, 准教授 (30377618)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 系統進化 / 系統地理 / 進化生態 / 進化発生 / 単為生殖 / 遺伝構造 / 遺伝子浸透 / 地史

Outline of Final Research Achievements

The burrowing mayfly Ephoron shigae is distributed East Asia. Some populations are bisexual, and others are unisexual. In general, parthenogenetic organisms are often found in harsh environments, such as at high latitudes and altitudes, in xeric as opposed to mesic conditions, in isolated habitats, and at the peripheral regions of the taxon’s distribution range. However, the distributions of bisexual and unisexual populations overlap broadly in their respective geographical ranges. In the analysis of mtDNA (16S, COI), we revealed that unisexual populations were of monophyletic origin and recently differentiated in western Japan. In the nuDNA EF-1a, boule analysis, parthenogenetic strains had two genotypes, while specimens of bisexual lineage had 20 genotypes. These results are consistent with an automixis mode of reproduction for the parthenogenetic strains. Furthermore, there would be no gene flow between the specimens of the bisexual lineage and those of the parthenogenetic strain.

Free Research Field

進化生物学