Fig. 2.—

A set of ecological relationships with different nonindependence of species is shown. This includes the classic predator–prey cycles, competition leading to anticorrelation, commensalism where the presence of one species is beneficial to the other, mutualism where two species are positively correlated as mutually beneficial, and amensalism, where the presence of one species is deleterious to the other. The statistical signatures of these relationships can be identified in metagenomic data, where samples vary either across time or geographically.