Aizenberg-Gershtein Yana, Izhaki Ido, Halpern Malka
Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Mount Carmel, Haifa, Israel.
Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa, Oranim, Tivon, Israel.
Microb Ecol. 2017 Jul;74(1):128-139. doi: 10.1007/s00248-017-0935-9. Epub 2017 Jan 20.
Microbial model systems are very useful in addressing macro-ecological questions. Two major theories exist to date, to explain the community structure of organisms: (1) the dispersal (neutral) assembly theory which predicts that community similarity decreases with increasing geographic distance, independent of any environmental variables, and (2) the niche assembly theory which predicts that the communities' compositions are more homogeneous among sites characterized by similar environmental conditions. Our study system offered a unique opportunity to investigate the relative role of environmental conditions and spatial factors in shaping community composition. We explored the bacterial community composition (BCC) of Nicotiana glauca floral nectar using the Illumina MiSeq technique at three spatial scales (plants, site, and region) and two taxonomic levels. Floral nectar samples were collected from 69 N. glauca plants at 11 different sites along a 200-km transect in Israel, along three biogeographic regions. A distance decay of BCC was found among all plants throughout Israel, but such pattern was not found among either sites or biogeographical regions. The BCC was also governed by environmental conditions in all examined scales (from the plant up to the biogeographical region). We also found that taxonomic resolution (89 and 97% sequence identity for clustering operational taxonomic units) affected the results of these BCC analyses. Hence, our study revealed that the BCC in N. glauca floral nectar is shaped by both the environmental conditions and the distance between plants, depending on the sampling scale under examination as well as by taxonomic resolution.
微生物模型系统在解决宏观生态问题方面非常有用。迄今为止，存在两种主要理论来解释生物群落结构：（1）扩散（中性）组装理论，该理论预测群落相似度会随着地理距离的增加而降低，与任何环境变量无关；（2）生态位组装理论，该理论预测在具有相似环境条件的地点之间，群落组成更加同质化。我们的研究系统提供了一个独特的机会来研究环境条件和空间因素在塑造群落组成中的相对作用。我们使用Illumina MiSeq技术在三个空间尺度（植物、地点和区域）和两个分类水平上探索了黄花烟草花蜜的细菌群落组成（BCC）。沿着以色列境内200公里的样带，在三个生物地理区域的11个不同地点，从69株黄花烟草植物上采集了花蜜样本。在以色列所有植物中都发现了BCC的距离衰减，但在地点或生物地理区域中均未发现这种模式。在所有考察尺度（从植物到生物地理区域）上，BCC也受环境条件的支配。我们还发现分类分辨率（用于聚类操作分类单元的序列同一性为89%和97%）影响了这些BCC分析的结果。因此，我们的研究表明，黄花烟草花蜜中的BCC是由环境条件和植物之间的距离塑造的，这取决于所考察的采样尺度以及分类分辨率。
