Fig. 5: The conceptual diagram of the “hunger games” hypothesis. The species abundance in natural bacterial communities is collectively determined by the genomic trait of rrn copy number, ecological interaction, and nutrient availability.

Nutrient-scarce environments favor species with low rrn copy numbers, while nutrient-rich environment favors species with high rrn copy numbers. In nutrient-scarce environments, cooperation, e.g., mutually benefit from metabolite exchange, is promoted to alleviate resource limitation. By contrast, there are more ecological interactions among species in nutrient-rich environments, in which competition plays a larger role.