Parallel evolution of alternate morphotypes of Chryseobacterium gleum during experimental evolution with Caenorhabditis elegans.

Microbial evolution within polymicrobial communities is a complex process. Here we report within-species diversification within multi-species microbial communities during experimental evolution with the nematode Caenorhabditis elegans. We describe morphological diversity in the target species Chryseobacterium gleum, which developed a novel colony morphotype in a small number of replicate communities. Alternate morphotypes co-existed with original morphotypes in communities, as well as in single-species experiments using evolved isolates. We found that the original and alternate morphotypes differed in motility and in spatial expansion in the presence of C. elegans. This study provides insight into the emergence and maintenance of intra-species diversity in the context of microbial communities.