Shifts in morphology and diet of non-native sticklebacks introduced into Japanese crater lakes

Authors

  • Tatsuya Adachi,

    1. Division of Ecology and Evolutionary Biology, Graduate School of Life Sciencefs, Tohoku University, Sendai, Miyagi 980-8578, Japan
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  • Asano Ishikawa,

    1. Ecological Genetics Laboratory, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
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  • Seiichi Mori,

    1. Biological Laboratory, Gifu-keizai University, Ogaki, Gifu 503-8550, Japan
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  • Wataru Makino,

    1. Division of Ecology and Evolutionary Biology, Graduate School of Life Sciencefs, Tohoku University, Sendai, Miyagi 980-8578, Japan
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  • Manabu Kume,

    1. Biological Laboratory, Gifu-keizai University, Ogaki, Gifu 503-8550, Japan
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  • Masakado Kawata,

    1. Division of Ecology and Evolutionary Biology, Graduate School of Life Sciencefs, Tohoku University, Sendai, Miyagi 980-8578, Japan
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  • Jun Kitano

    1. Division of Ecology and Evolutionary Biology, Graduate School of Life Sciencefs, Tohoku University, Sendai, Miyagi 980-8578, Japan
    2. Ecological Genetics Laboratory, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
    3. PRESTO, Japan Science and Technology Agency, Honcho Kawaguchi, Saitama 332-0012, Japan
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  • This research is supported by JST PRESTO program, Asahi Glass Foundation, Grant-in-Aid for Young Scientist (B) (22770075) and Grant-in-Aid for Scientific Research on Innovative Areas (23113007 and 23113001) from the Ministry of Education, Science, Sports, and Culture to J. K. and NIG Collaborative Research Program (2011-A68, A69). A. I. is a fellow of the Japan Society of Promotion of Science.

Jun Kitano, Ecological Genetics Laboratory, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan. Tel: 81-55-981-9415; Fax: 81-55-981-9416; E-mail: jkitano@lab.nig.ac.jp

Abstract

An increasing number of exotic animals are causing ecological problems. Therefore, for better ecosystem management, it is important to understand how exotic species colonize and adapt to novel environments. The threespine sticklebacks (Gasterosteus aculeatus) can be a good vertebrate model system to explore the ecological and genetic mechanisms of adaptation not only in natural populations, but also in non-native populations. Although morphological changes have been documented in several introduced populations of stickleback, little is known about the dietary changes during colonization into novel environments. Here, we investigated the morphological and dietary changes of exotic threespine stickleback populations introduced into three Japanese crater lakes (Lake Towada, Lake Kussharo, and Lake Shikotsu). Sticklebacks were introduced into the crater lakes likely along with salmonids transplanted for aquaculture. The stickleback population in Lake Kussharo had multiple mitochondrial haplotypes and had larger phenotypic variances than other crater lake stickleback populations that had only one mitochondrial haplotype. Compilation of historical data on the morphology and stomach contents of the Lake Towada stickleback population showed that substantial shifts in body size and stomach contents occurred after colonization. Some of these changes may be related to an outbreak of the Schistocephalus parasite. These results suggest that sticklebacks can change their morphology and trophic ecology when they colonize novel environments. Therefore, extreme care should be taken when salmonids are transported between watersheds for aquaculture and that long-term monitoring of exotic species is essential for ecosystem management. In addition, further genetic studies on phenotypic changes in crater lake sticklebacks would help elucidate the genetic mechanisms underlying the adaptation of exotic fishes to novel environments.

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