COS 77-5 - CANCELLED - Animal microbiomes assembled with inter-host dispersal are less resistant to environmental disturbance than microbiomes assembled in isolation

Abstract: Microbiomes associated with animal hosts can play a pivotal role in host health and fitness. However, disturbances such as medical intervention or environmental change can alter the diversity and composition of animal-associated microbial communities. Evidence from mouse models suggests that dispersal of microbes from an undisturbed host may enhance microbiome recovery for a disturbed host. Less is known about how inter-host dispersal during early microbiome assembly can mediate microbiome resistance to future disturbance. The aim of this study was to determine if microbial communities assembled in isolated hosts without inter-host dispersal are less resistant to environmental disturbance than communities assembled in hosts with microbial dispersal from other hosts. To address this aim, we raised larval zebrafish (Danio rerio) in solitary flasks or in cohoused flasks with 10 individuals from zero to six days post fertilization. Then, half of all flasks were exposed to sublethal antibiotics (50 ng/ml ciprofloxacin) for 24 hours to simulate an environmental disturbance. At seven days post fertilization, larval zebrafish guts were dissected and processed for 16S community profiling. Overall, cohoused fish microbiomes were more variable than solitary fish microbiomes suggesting that dispersal results in stochastic community assembly. We found that for cohoused fish microbiomes assembled with dispersal, antibiotics caused a significant change in community composition and a significant increase in Shannon Diversity. In contrast, antibiotic disturbance had no effect on solitary fish microbiomes, which were indistinguishable from those of undisturbed cohoused fish. In conclusion, this study shows that inter-host microbial dispersal between larval zebrafish decreases community resistance to antibiotic disturbance. In the context of metacommunity theory, this suggests that dispersal between local communities may hamper resistance to environmental disturbance through the stochastic colonization of communities with disturbance-tolerant taxa. For populations of social hosts, understanding how microbial dispersal contributes to community variation will be crucial to preserving microbiome function in the face of increasing environmental disturbance.