TY - JOUR T1 - Evolutionary stability of microbial communities with antibiotic degrading species JF - bioRxiv DO - 10.1101/045732 SP - 045732 AU - Eric D. Kelsic AU - Kalin Vetsigian AU - Roy Kishony Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/04/22/045732.abstract N2 - A major puzzle in ecology is how antibiotic resistant, sensitive and producer species coexist in close proximity. Recently, we showed that antibiotic degrading species dramatically alter community dynamics: replacing intrinsic resistance with resistance through degradation generates stable communities resilient to spatial mixing, large species abundance perturbations, changes in interaction strengths, and differences in species growth rates1. In addition to ecological stability, it is interesting to consider evolutionary stability of these communities to the appearance of cheater species that either cease production or degradation of antibiotics. Our investigation of evolutionary stability of cyclical 3-species communities revealed that these communities are robust to cheaters that stop degrading antibiotics. Our simulations also showed that cheaters that stop producing antibiotics do not take over the community1, yet they can transiently invade and cause community collapse2. In the analytical approximation we initially investigated, production cheaters with a small fitness advantage can invade the community simply because the benefit of inhibiting competitors is shared among all cells2. Here, we consider evolutionary stability to cheaters in our complete model1, where spatial mixing is introduced only after a short range colonization step. In this regime, an antibiotic producer cell directly benefits from killing nearby competitor species as it has a greater chance of colonizing the newly voided spaces created by the action of its antibiotic. Simulating response to cheater invasions for the cyclical three species community and for random 4-species ecologically stable topologies, we find that these communities can be fully resilient to both degradation and production cheaters. The strength of selection against cheaters varies with the area of the zone of inhibition around producers and is maximized for weak inhibition, where there is less overlap between the killing zones of neighboring cells. These results may aid the construction of complex synthetic communities that are both ecological and evolutionary stable. ER -