Ito Natsumi, Iwanaga Hiroko, Charles Suliana, Diway Bibian, Sabang John, Chong Lucy, Nanami Satoshi, Kamiya Koichi, Lum Shawn, Siregar Ulfah J, Harada Ko, Miyashita Naohiko T
Laboratory of Plant Genetics, Graduate School of Agriculture, Kyoto University.
Sarawak Forestry Corporation.
Genes Genet Syst. 2017 Sep 12;92(1):1-20. doi: 10.1266/ggs.16-00013. Epub 2016 Dec 21.
Geographical variation in soil bacterial community structure in 26 tropical forests in Southeast Asia (Malaysia, Indonesia and Singapore) and two temperate forests in Japan was investigated to elucidate the environmental factors and mechanisms that influence biogeography of soil bacterial diversity and composition. Despite substantial environmental differences, bacterial phyla were represented in similar proportions, with Acidobacteria and Proteobacteria the dominant phyla in all forests except one mangrove forest in Sarawak, although highly significant heterogeneity in frequency of individual phyla was detected among forests. In contrast, species diversity (α-diversity) differed to a much greater extent, being nearly six-fold higher in the mangrove forest (Chao1 index = 6,862) than in forests in Singapore and Sarawak (~1,250). In addition, natural mixed dipterocarp forests had lower species diversity than acacia and oil palm plantations, indicating that aboveground tree composition does not influence soil bacterial diversity. Shannon and Chao1 indices were correlated positively, implying that skewed operational taxonomic unit (OTU) distribution was associated with the abundance of overall and rare (singleton) OTUs. No OTUs were represented in all 28 forests, and forest-specific OTUs accounted for over 70% of all detected OTUs. Forests that were geographically adjacent and/or of the same forest type had similar bacterial species composition, and a positive correlation was detected between species divergence (β-diversity) and direct distance between forests. Both α- and β-diversities were correlated with soil pH. These results suggest that soil bacterial communities in different forests evolve largely independently of each other and that soil bacterial communities adapt to their local environment, modulated by bacterial dispersal (distance effect) and forest type. Therefore, we conclude that the biogeography of soil bacteria communities described here is non-random, reflecting the influences of contemporary environmental factors and evolutionary history.
对东南亚（马来西亚、印度尼西亚和新加坡）的26片热带森林以及日本的两片温带森林土壤细菌群落结构的地理变异进行了调查，以阐明影响土壤细菌多样性和组成生物地理学的环境因素及机制。尽管环境存在显著差异，但细菌门的比例相似，除了砂拉越的一片红树林外，所有森林中酸杆菌门和变形菌门都是优势菌门，不过在不同森林中各菌门的频率存在高度显著的异质性。相比之下，物种多样性（α-多样性）差异更大，红树林中的物种多样性（Chao1指数 = 6,862）几乎是新加坡和砂拉越森林（约1,250）的六倍。此外，天然龙脑香混交林的物种多样性低于相思树和油棕种植园，这表明地上树木组成不会影响土壤细菌多样性。香农指数和Chao1指数呈正相关，这意味着操作分类单元（OTU）分布的偏差与总体和稀有（单例）OTU的丰度有关。在所有28片森林中都没有出现相同的OTU，特定森林的OTU占所有检测到的OTU的70%以上。地理位置相邻和/或森林类型相同的森林具有相似的细菌物种组成，并且在物种差异（β-多样性）与森林之间的直线距离之间检测到正相关。α-多样性和β-多样性均与土壤pH值相关。这些结果表明，不同森林中的土壤细菌群落很大程度上相互独立进化，并且土壤细菌群落适应其当地环境，受到细菌扩散（距离效应）和森林类型的调节。因此，我们得出结论，这里描述的土壤细菌群落生物地理学是非随机的，反映了当代环境因素和进化历史的影响。
