The role of interspecific interactions in microbial speciation

Background/Question/Methods

Microbes are the main drivers of biogeochemical cycles, and they play a key role in shaping ecosystems. In nature, they almost always exist within communities and exhibit great species diversity. However, the ecological and evolutionary processes that could explain this diversity are not fully understood. Bacterial communities experience ecological interactions that have been shown to influence speciation. Previous studies have focused on how competition leads to diversification, but the effects that commensal interactions have on diversification are understudied. We used a synthetic microbial community composed of Acinetobacter johnsonii and Pseudomonas putida, where Acinetobacter cross feeds benzoate to Pseudomonas. This is a model community for studying metabolic interaction in microbial systems. We allowed them to evolve for two hundred generations and performed whole-genome sequencing to detect mutations in the experimental lines.

Results/Conclusions

Preliminary data shows Pseudomonas acquired de novo mutations enriched by selection leading to divergence in response to the interspecific commensal interaction with Acinetobacter. These results may indicate that commensal interactions between species could lead to divergence and possible speciation. We expect to find that interspecific commensalism can lead to intraspecific competition causing diversification. This process can play a key role in accounting for the great bacterial diversity that we observe in nature.