Section for Genetic Ecology and Evolution, Department of Biology, Aarhus University, Aarhus, Denmark.
Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark.
J Evol Biol. 2023 Dec;36(12):1684-1694. doi: 10.1111/jeb.14228. Epub 2023 Sep 30.
Within a given species, considerable inter-individual, spatial, and temporal variation in the composition of the host microbiome exists. In group-living animals, social interactions homogenize microbiome composition among group members, nevertheless divergence in microbiome composition among related groups arise. Such variation can result from deterministic and stochastic processes. Stochastic changes, or ecological drift, can occur among symbionts with potential for colonizing a host and within individual hosts, and drive divergence in microbiome composition among hosts or host groups. We tested whether ecological drift associated with dispersal and foundation of new groups cause divergence in microbiome composition between natal and newly formed groups in the social spider Stegodyphus dumicola. We simulated the initiation of new groups by splitting field-collected nests into groups of 1, 3, and 10 individuals respectively, and compared variation in microbiome composition among and within groups after 6 weeks using 16S rRNA gene sequencing. Theory predicts that ecological drift increases with decreasing group size. We found that microbiome composition among single founders was more dissimilar than among individuals kept in groups, supporting this prediction. Divergence in microbiome composition from the natal nest was mainly driven by a higher number of non-core symbionts. This suggests that stochastic divergence in host microbiomes can arise during the process of group formation by individual founders, which could explain the existence of among-group variation in microbiome composition in the wild. Individual founders appear to harbour higher relative abundances of non-core symbionts compared with founders in small groups, some of which are possible pathogens. These symbionts vary in occurrence with group size, indicating that group dynamics influence various core and non-core symbionts differently.
在给定的物种中，宿主微生物组的组成在个体间、空间和时间上存在很大差异。在群居动物中，社会互动使群体成员的微生物组组成趋于同质化，但相关群体之间的微生物组组成仍存在差异。这种差异可能是由确定性和随机性过程造成的。共生体之间可能发生随机变化或生态漂移，这些共生体有可能定植宿主，并在个体宿主内发生，从而导致宿主或宿主群体之间微生物组组成的差异。我们测试了与扩散和新群体形成相关的生态漂移是否会导致社会蜘蛛 Stegodyphus dumicola 的出生地和新形成的群体之间微生物组组成的差异。我们通过将野外采集的巢穴分别分成 1、3 和 10 个个体的群体来模拟新群体的形成，并在 6 周后使用 16S rRNA 基因测序比较群体之间和群体内的微生物组组成变化。理论预测，生态漂移随群体规模的减小而增加。我们发现，单个创始人之间的微生物组组成比保持在群体中的个体之间的差异更大，这支持了这一预测。从出生地巢穴的微生物组组成的差异主要是由更多的非核心共生体驱动的。这表明，在个体创始人形成群体的过程中，宿主微生物组可能会出现随机差异，这可以解释野生环境中微生物组组成的群体间差异的存在。与小群体中的创始人相比，单个创始人似乎拥有更高比例的非核心共生体，其中一些可能是病原体。这些共生体的出现频率随群体大小而变化，表明群体动态对各种核心和非核心共生体的影响不同。
