Red queen coevolution between parasites and their hosts is thought to have had profound effects on the evolution of life.  Coevolution in this model is driven by the allele-for-allele matching of a parasite's counter-defenses to specialized host defenses. Such dynamics have been predicted to favor the evolution of sexual recombination, drive the evolution of mutation rates, promote local adaptation, and lead to the diversification of species.  While there is empirical evidence for these predictions, few direct, experimental tests of the effects of allele-for-allele coevolution have been preformed.  In this talk, we will describe the development of a model phage (bacterial virus) and bacterial system amenable to studying the effects of such dynamics.

Results/Conclusions

Apparent allele-for-allele coevolution was observed in communities of bacteria and phage, with both genetic and phenotypic support.  We also showed that both ecological variables, which we manipulate, and the genetic architectures of the species seem to influence the coevolutionary outcomes in this system.  In particular, ongoing cycles of coevolution were observed only in particular resource environments where the bacteria paid a high cost, in terms of their competitiveness, for evolving phage resistance.  These environments are ones in which the limiting resource enters the cell via the same surface protein that the phage targets for entry into the cell.