Hata Hiroki, Tanabe Akifumi S, Yamamoto Satoshi, Toju Hirokazu, Kohda Masanori, Hori Michio
Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo, Matsuyama, Ehime, Japan.
Graduate School of Global Environmental Studies, Kyoto University, Sakyo, Kyoto, Japan.
BMC Biol. 2014 Oct 29;12:90. doi: 10.1186/s12915-014-0090-4.
Lake Tanganyika, an ancient lake in the Great Rift Valley, is famous for the adaptive radiation of cichlids. Five tribes of the Cichlidae family have acquired herbivory, with five ecomorphs: grazers, browsers, scrapers, biters and scoopers. Sixteen species of the herbivorous cichlids coexist on a rocky littoral slope in the lake. Seven of them individually defend feeding territories against intruding herbivores to establish algal farms. We collected epiphyton from these territories at various depths and also gathered fish specimens. Algal and cyanobacteria community structures were analysed using the amplicon-metagenomic method.
Based on 454-pyrosequencing of SSU rRNA gene sequences, we identified 300 phototrophic taxa, including 197 cyanobacteria, 57 bacillariophytes, and 31 chlorophytes. Algal farms differed significantly in their composition among cichlid species, even in the same ecomorph, due in part to their habitat-depth segregation. The algal species composition of the stomach contents and algal farms of each species differed, suggesting that cichlids selectively harvest their farms. The stomach contents were highly diverse, even between species in the same tribe, in the same feeding ecomorph.
In this study, the amplicon-metagenomic approach revealed food niche separation based on habitat-depth segregation among coexisting herbivorous cichlids in the same ecomorphs in Lake Tanganyika.
坦噶尼喀湖是东非大裂谷中的一个古老湖泊，以丽鱼科鱼类的适应性辐射而闻名。丽鱼科的五个部落已经获得了草食习性，有五种生态形态：食草者、食叶者、刮食者、咬食者和铲食者。16种草食性丽鱼科鱼类共存于该湖的岩石沿岸斜坡上。其中7种会各自保卫觅食领地，抵御入侵的草食动物，以建立藻类养殖场。我们在不同深度从这些领地采集了附生植物，还收集了鱼类标本。使用扩增子宏基因组方法分析了藻类和蓝细菌的群落结构。
基于SSU rRNA基因序列的454焦磷酸测序，我们鉴定出300个光合生物分类单元，包括197种蓝细菌、57种硅藻和31种绿藻。即使是同一生态形态的丽鱼科鱼类，其藻类养殖场的组成在不同物种之间也存在显著差异，部分原因是它们在栖息地深度上的隔离。每个物种的胃内容物和藻类养殖场的藻类物种组成不同，这表明丽鱼科鱼类会有选择地收获它们的养殖场。即使是同一部落、同一觅食生态形态的物种之间，胃内容物也高度多样化。
在本研究中，扩增子宏基因组方法揭示了坦噶尼喀湖同一生态形态中共存的草食性丽鱼科鱼类基于栖息地深度隔离的食物生态位分离。
