Figure 2.

Environmental factors reduce microbial diversity because of the loss of predatory species. Gut microbiota may be seen as a complex network of many interacting species (nodes) with several kinds of interactions (links). Predators (in red) are key species that maintain the diversity of the microbiota by direct impact on preys (yellow) and indirect effect on other related species (blue). According to Voltera equations, loss of predators causes an increase number of preys but a loss of diversity. We propose that in industrialized countries environmental risk factors reduces the predators in the network causing LOMD.