Hu Yi, Łukasik Piotr, Moreau Corrie S, Russell Jacob A
Department of Biology, Drexel University, Philadelphia, PA, 19104, USA.
Department of Science and Education, Field Museum of Natural History, Chicago, IL, 60605, USA.
Mol Ecol. 2014 Mar;23(6):1284-1300. doi: 10.1111/mec.12607. Epub 2013 Dec 31.
Insect guts are often colonized by multispecies microbial communities that play integral roles in nutrition, digestion and defence. Community composition can differ across host species with increasing dietary and genetic divergence, yet gut microbiota can also vary between conspecific hosts and across an individual's lifespan. Through exploration of such intraspecific variation and its correlates, molecular profiling of microbial communities can generate and test hypotheses on the causes and consequences of symbioses. In this study, we used 454 pyrosequencing and TRFLP to achieve these goals in an herbivorous ant, Cephalotes varians, exploring variation in bacterial communities across colonies, populations and workers reared on different diets. C. varians bacterial communities were dominated by 16 core species present in over two-thirds of the sampled colonies. Core species comprised multiple genotypes, or strains and hailed from ant-specific clades containing relatives from other Cephalotes species. Yet three were detected in environmental samples, suggesting the potential for environmental acquisition. In spite of their prevalence and long-standing relationships with Cephalotes ants, the relative abundance and genotypic composition of core species varied across colonies. Diet-induced plasticity is a likely cause, but only pollen-based diets had consistent effects, altering the abundance of two types of bacteria. Additional factors, such as host age, genetics, chance or natural selection, must therefore shape natural variation. Future studies on these possibilities and on bacterial contributions to the use of pollen, a widespread food source across Cephalotes, will be important steps in developing C. varians as a model for studying widespread social insect-bacteria symbioses.
昆虫肠道中通常定殖着多种微生物群落，这些群落在营养、消化和防御方面发挥着不可或缺的作用。随着饮食和遗传差异的增加，不同宿主物种的群落组成可能会有所不同，然而，同一物种宿主之间以及个体的整个生命周期内，肠道微生物群也可能存在差异。通过探索这种种内变异及其相关因素，对微生物群落进行分子分析可以生成并检验关于共生关系的原因和后果的假设。在本研究中，我们使用454焦磷酸测序和末端限制性片段长度多态性分析（TRFLP），在食草蚂蚁Cephalotes varians中实现这些目标，探索不同菌落、种群以及取食不同食物的工蚁之间细菌群落的变异。C. varians的细菌群落由16个核心物种主导，这些物种存在于超过三分之二的采样菌落中。核心物种包括多个基因型或菌株，来自包含其他Cephalotes物种亲属的蚂蚁特异性进化枝。然而，在环境样本中检测到了其中三种，这表明存在从环境中获取的可能性。尽管这些核心物种普遍存在且与Cephalotes蚂蚁有着长期的关系，但不同菌落中核心物种的相对丰度和基因型组成有所不同。饮食诱导的可塑性可能是一个原因，但只有以花粉为基础的饮食有一致的影响，改变了两种细菌的丰度。因此，其他因素，如宿主年龄、遗传、偶然性或自然选择，必定会影响自然变异。未来对这些可能性以及细菌对花粉利用（花粉是Cephalotes广泛的食物来源）的贡献的研究，将是把C. varians发展成为研究广泛的社会性昆虫 - 细菌共生关系模型的重要步骤。
