The youngest split in sympatric schizothoracine fish (Cyprinidae) is shaped by ecological adaptations in a Tibetan Plateau glacier lake

Authors

  • KAI ZHAO,

    1. Key Laboratory of Adaptation and Evolution of Plateau Biota (AEPB), Northwest Plateau Institute of Biology, Chinese Academy of Sciences, 810001 Xining, Qinghai, China
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  • ZI YUAN DUAN,

    1. Laboratory of Fish Phylogenetics and Biogeography, Institute of Hydrobiology, Chinese Academy of Sciences, 430072 Wuhan, Hubei, China
    2. Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, 100101 Beijing, China
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  • ZUO GANG PENG,

    1. Laboratory of Fish Phylogenetics and Biogeography, Institute of Hydrobiology, Chinese Academy of Sciences, 430072 Wuhan, Hubei, China
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    • §

      Present address: School of Biology, Georgia Institute of Technology, Atlanta 30332, GA, USA.

  • SONG CHANG GUO,

    1. Key Laboratory of Adaptation and Evolution of Plateau Biota (AEPB), Northwest Plateau Institute of Biology, Chinese Academy of Sciences, 810001 Xining, Qinghai, China
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  • JUN BING LI,

    1. Laboratory of Fish Phylogenetics and Biogeography, Institute of Hydrobiology, Chinese Academy of Sciences, 430072 Wuhan, Hubei, China
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  • SHUN PING HE,

    1. Laboratory of Fish Phylogenetics and Biogeography, Institute of Hydrobiology, Chinese Academy of Sciences, 430072 Wuhan, Hubei, China
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  • XIN QUAN ZHAO

    1. Key Laboratory of Adaptation and Evolution of Plateau Biota (AEPB), Northwest Plateau Institute of Biology, Chinese Academy of Sciences, 810001 Xining, Qinghai, China
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  • Kai Zhao and Ziyuan Duan made equal contributions to this study.

  • Kai Zhao and Ziyuan Duan is interested in molecular evolution and biogeography of animals, with special interests in speciation and the adaptive evolution. The research group of Xinquan Zhao, Shunping He, and Zuogang Peng focuses on the animal ecology and population biology.

Xin Quan Zhao, Fax: +86 971 6143282; E-mail: xqzhao@nwipb.ac.cn; Shun Ping He, Fax: +86 27 68780071; E-mail: clad@ihb.ac.cn

Abstract

Although new empirical evidence shows that sympatric speciation has occurred in some species, there are few indisputable model organisms for this process of speciation. The two subspecies (Gymnocypris eckloni eckloni and G. e. scoliostomus) of the schizothoracine Gymnocypris fish species complex from a small glacier lake in the Tibetan Plateau, Lake Sunmcuo, fit several of the key characteristics of the sympatric speciation model. We used combined mitochondrial control region sequences and the cytochrome b gene (1894 bp) to address the phylogenetics and population genetics of 232 specimens of G. e. eckloni and G. e. scoliostomus, as well as all of its closely related sister species. We found that: (i) a total of four old lineages were uncovered in the widespread G. e. eckloni, of which only one was shown to be shared with all G. e. scoliostomus individuals and (ii) the new subspecies (G. e. scoliostomus) evolved in Lake Sunmcuo from the ancestral G. e. eckloni population within approximately 0.057 Ma. These two taxa of the species complex are morphologically distinct, and reproductive isolation is further suggested. Ecological disruptive selection based on morphological traits (e.g. mouth cleft characters) and food utilization may be a mechanism of incipient speciation of two sympatric populations within Lake Sunmcuo. This study provides the first genetic evidence for sympatric speciation in the schizothoracine fish.

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