西藏羊卓雍错高原裸鲤肠道寄生蠕虫的群落生态

COMMUNITY ECOLOGY OF INTESTINAL HELMINTHS IN GYMNOCYPRIS WADDELLII FROM YAMDROK LAKE, TIBET AUTONOMOUS REGION, CHINA

  • 摘要: 为研究西藏羊卓雍错Yamdrok Lake高原裸鲤肠道寄生蠕虫的群落生态, 探索寄生虫与西藏高原环境和独特的鱼类宿主三者之间的相互关系, 以肠道寄生蠕虫为对象, 于2020年7月对180尾高原裸鲤Gymnocypris waddellii 雌性120尾, 雄性60尾, 全长22.20—49.20 cm, 平均全长(36.76±4.18) cm, 体重77.3—896.7 g, 平均体重(425.92±148.27) g进行了剖检, 对群落结构和种间关系等群落生态进行了分析。羊卓雍错高原裸鲤肠道寄生蠕虫群落由5个物种构成, 分别为聂氏似短节绦虫Parabreviscolex niepini、对盲囊线虫Contracaecum eudyptulae、束首线虫未定种Streptocara sp.、新棘吻虫未定种Neoechinorhynchus sp.和异肉吸虫未定种Allocreadium sp.。感染率从高到低依次为新棘吻虫未定种、聂氏似短节绦虫异肉吸虫未定种、对盲囊线虫和束首线虫未定种。平均丰度从高到低依次为聂氏似短节绦虫、新棘吻虫未定种、束首线虫未定种、异肉吸虫未定种和对盲囊线虫。群落的Margalef物种丰富度指数为0.59, Shannon-Wiener多样性指数为1.26, Pielou均匀度指数为0.83, Berger-Parker优势度指数为0.50, 优势物种为聂氏似短节绦虫。有4组物种间存在正关联, 关联性从高到代依次为: 新棘吻虫未定种与异肉吸虫未定种、对盲囊线虫与新棘吻虫未定种、对盲囊线虫与异肉吸虫未定种、对盲囊线虫与束首线虫未定种。其他寄生蠕虫物种两两不存在种间关联。从感染与否看, 被感染的宿主数量超过采样群体宿主数量的一半, 其中, 以感染1种寄生虫的宿主出现频次最高, 感染2种寄生虫的宿主出现频次也较高, 3种和4种寄生虫共同感染的宿主出现频次明显降低, 未发现5种寄生虫同时感染的宿主。与同位于西藏南部, 并曾经相连的哲古措Chugutso Lake相比, 两个湖泊尽管地理位置相近, 宿主鱼类种类相同, 寄生蠕虫物种组成一致, 但羊卓雍错高原裸鲤肠道寄生蠕虫群落具有自身特点, 即更高的平均丰度, 绝大部分寄生蠕虫种群也具有更高的感染率, 群落中的优势物种也与哲古措不同。种间关联被用来判断肠道寄生蠕虫群落中各种群两两间是否存在共存或排斥关系, 即种间亲和性。在羊卓雍错高原裸鲤肠道寄生蠕虫群落中, 新棘吻虫未定种与异肉吸虫未定种种间亲和性最高。但这种关系并不稳定, 会随着水生态环境和群落中物种组成等的变化而变化。共感染的宿主出现频次变化提示, 随着一个亚群落中物种数的增加, 种间的相互作用越大, 保持共存也越难。

     

    Abstract: This paper studies the community ecology of intestinal helminths in Gymnocypris waddellii from Yamdrok Lake, Tibet Autonomous Region, China, and the interactions among the parasite community, environmental conditions of the Tibet Plateau, and unique hosts. In July 2020, 180 samples total length: 22.20—49.20 cm; average length: (36.76±4.18) cm; weight: 77.3—896.7 g; average weight: (425.92±148.27) g, including 120 females and 60 males, were dissected for the analysis of community structure, interspecific relationship and other aspects of community ecology. Intestinal helminths in the samples consist of 5 species: Neoechinorhynchus sp., Parabreviscolex niepini, Allocreadium sp., Contracaecum eudyptulae and Streptocara sp., if ranked by the prevalence of infection from the highest to the lowest (or Parabreviscolex niepini, Neoechinorhynchus sp., Streptocara sp., Allocreadium sp. and Contracaecum eudyptulae, if ranked by the mean abundance of infection from the highest to the lowest). The Margalef index of species richness is 0.59, the Shannon-Wiener index of species diversity is 1.26, the Pielou index of species evenness is 0.83, and the Berger- Parker index of species dominance is 0.50. Parabreviscolex niepini is the dominant species. Positive correlations are found between 4 groups of species: Neoechinorhynchus sp. and Allocreadium sp.; Contracaecum eudyptulae and Neoechinorhynchus sp.; Contracaecum eudyptulae and Allocreadium sp.; Contracaecum eudyptulae and Streptocara sp., if ranked by the degree of correlation from the highest to the lowest. No interspecific association is observed between other species of parasitic worms. The number of infected hosts is over 50% of the sample size. The number of hosts infected with one parasite species is the highest, followed by the number of hosts infected with 2 parasite species. Hosts infected with 3 or 4 parasite species are less common, and there are no hosts infected with 5 parasite species. In comparison with the same parasite species in the same hosts from the adjacent Chugutso Lake, which was once connected with Yamdrok Lake in the south of Tibet Autonomous Region, intestinal helminth communities in hosts from Yamdrok Lake feature higher values of prevalence and mean abundance of infection, and different dominant species. Interspecific compatibility, a measure of interspecific association, is used to describe the coexistence or competitive exclusion between two intestinal helminth communities in the hosts from Yamdrok Lake. It’s found that the interspecific compatibility between Nceoechinorhynchus sp. and Allocreadium sp. is the highest but unstable, and it changes with the water environment and species composition in the communities. The variation in the number of hosts infected with more than one parasite species indicates that the difficulty in achieving coexistence increases when interspecific interaction grows with the increase of the number of species in a sub-community.

     

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