Print PageCoevolution - the process by which interacting species undergo reciprocal evolutionary change - is an important driving force underlying the generation and maintenance biodiversity. Recent advances in sequencing technology have enabled us to study the genomic dynamics of coevolutionary interactions at an unprecedented level of detail. We used Illumina resequencing technology to sequence whole genomes of bacteria (Escherichia coli B) and bacteriophage (T3) that coevolved in the laboratory for approximately 200 bacterial generations. We sequenced the ancestral bacterial clone as well as two bacteria that had evolved resistance to the ancestral phage. We also sequenced the ancestral phage and a derived phage type that is able to infect both the ancestral bacterial genotype and the resistant clones.We examine how these genetic changes cause changes in ecological interactions among community members, and subsequently how they affect community- and ecosystem-level properties such as the relative abundances of species in the community and the equilibrium concentration of resource in the environment.
Results/Conclusions
We found that the two resistant bacterial clones evolved resistance to ancestral phage in different ways -- one through a single nucleotide substitution and the other through a large genomic deletion. Unlike the derived bacterial genomes which each showed a single mutational event distinguishing derived strains from the ancestor, the host-range phage accumulated twenty-seven substitutions by day nineteen of the experiment. Several of these substitutions lie in genes previously-shown to be involved in the bacteria-bacteriophage interaction. We found that these genetic changes alter properties of the community like the relative abundances of interacting species and the concentration of resource in the environment.
