Invasion and molecular evolution of Daphnia pulex in Japan

Mika So, Hajime Ohtsuki, Wataru Makino, Seiji Ishida, Hitoshi Kumagai, Kenyu G. Yamaki, Jotaro Urabe

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)


    We examined Daphnia pulex in Japan to clarify if they were representative of indigenous populations or colonized recently. Phylogenetic analysis of mtDNA suggests that Japanese lineages of D. pulex are immigrants from North America, and are hybrids formed with Daphnia pulicaria prior to this immigration. Based on the mtDNA sequences, the D. pulex individuals aggregated into four distinct genetic groups (JPN 1-4) comprising a total of 21 haplotypes. Surprisingly, microsatellite analysis with 12 loci revealed only a single multilocus genotype per genetic group, suggesting that D. pulex populations in Japan are comprised of asexual individuals, derived from only four clones. According to the reported mutation rate of mtDNA, JPN 1 and 2, now widely distributed across Japan, were estimated to have invaded between 680 yr and 3400 yr ago, while JPN 3 and 4 colonized much more recently. Results also indicated that the invasion of some clones could not be attributed to recent human activities and most likely occurred by rare natural events. Since the evolutional longevity of asexual clones is thought to be limited, genetic diversity of D. pulex in Japan has the possibility of decreasing in the near future without addition of novel gene flow.

    Original languageEnglish
    Pages (from-to)1129-1138
    Number of pages10
    JournalLimnology and Oceanography
    Issue number4
    Publication statusPublished - 2015 Jul

    ASJC Scopus subject areas

    • Oceanography
    • Aquatic Science


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