PRJNA227198
Environmental bacterial community isolated from Cephalotes varians nest
Insect guts are often colonized by multi-species microbial communities that play integral roles in nutrition, digestion, and defense. 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 analyses to achieve these goals in an herbivorous ant, Cephalotes varians, exploring variation in bacterial communities across colonies, populations, and workers reared on different diets. We found that C. varians bacterial communities were dominated by 16 core species present in over two-thirds of the sampled colonies. Core bacteria hailed from ant-specific clades, with most having close relatives in other Cephalotes species. Yet three were detected in environmental samples, suggesting possible 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 just a few 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.