Evolution of the Earth Microbial Co-occurrence Network

Abstract Background: Co-occurrence pattern provides vital insight into complex microbial interactions of microbiomes. Although network analysis offers useful tools for describing microbial co-occurrence pattern, evolution of co-occurrence networks remains largely uncharacterized. Here, we simulated the evolution of the Earth microbial co-occurrence network and estimated topological fitness of its nodes based on the degree growth exponent.Results: We showed that the Earth microbial co-occurrence network evolved following Bianconi-Barabasi model. The Earth microbial co-occurrence network had reached to a stable status with around 500 nodes. Degree growth exponent was the major determinant of accumulated degree of taxa. The positive correlation between topological fitness and gene numbers in corresponding genomes suggests the intrinsic feature of topological fitness. The gamma distribution of topological fitness suggests the extinction of taxa with low topological fitness. We then examined the impact of node extinction and decay, finding that the link acquisition of hub nodes was not affected.Conclusions: This study glimpses the evolution feature of Earth microbial co-occurrence network and provides a framework for predicting potential hubs in the evolving network in future.