The Structure of Marine Phage Populations

Phage are the most abundant biological entities in the biosphere, with an estimated 10 particles on the planet. They also play a major role in carbon cycling; at least 25% of fixed carbon passes through phage. Their roles as predators of bacteria have important implications for possible marine CO2 sequestration. Metagenomic analyses show that the rank-abundance curve for marine phage communities follows a power law distribution. This distribution is consistent with a proposed, modified version of Lotka-Volterra predator-prey dynamics, where blooms of a specific microbial species lead to blooms of their corresponding phage and a subsequent decrease in abundance. The model predicts that the majority of phage genotypes in a population will be rare and it is unlikely that the most abundant phage genotype will be the same at different time points. The model is based on spatial-temporal heterogeneity and a power law phage decay, which are both supported by empirical data.