Rapid genomic changes in pathogenic Bacillus thuringiensis during adaptation to its nematode host

Bacillus thuringiensis is a pathogenic bacterium of invertebrates with a wide host spectrum, including the nematode Caenorhabditis elegans. We studied its ability to adapt to the nematode host with the help of an evolution experiment, during which a mixture of B. thuringiensis strains was either coevolved with C. elegans (coevolution treatment), adapted to a non-changing host population (one-sided adaptation), or evolved in the absence of the host (control evolution). Experimental evolution produced distinct phenotypic changes in virulence and also other life-history traits. We studied the analysis of the genetic basis of evolutionary changes based on whole-genome sequencing of replicate populations.