Background. A mismatch has emerged between models and data of host-parasite evolution. Theory readily predicts that parasites can promote host diversity through mechanisms such as disruptive selection. Yet, despite these predictions, empirical evidence for parasite-mediated increases in host diversity remains surprisingly scant. Results. Here, we document parasite-mediated disruptive selection on a natural Daphnia population during a parasite epidemic. The mean susceptibility of clones collected from the population before and after the epidemic did not differ, but clonal variance and broad-sense heritability of post-epidemic clones were significantly greater, indicating disruptive selection and rapid evolution. A maximum likelihood method that we developed for detecting selection on natural populations also suggests disruptive selection during the epidemic: the distribution of susceptibilities in the population shifted from unimodal prior to the epidemic to bimodal after the epidemic. Interestingly, this same bimodal distribution was retained after a generation of sexual reproduction. Conclusion. These results provide rare empirical support for parasite-driven increases in host genetic diversity, and suggest that this increase can occur rapidly. © 2008 Duffy et al; licensee BioMed Central Ltd.
Duffy, M. A., Brassil, C. E., Hall, S. R., Tessier, A. J., Cáceres, C. E., & Conner, J. K. (2008). Parasite-mediated disruptive selection in a natural Daphnia population. BMC Evolutionary Biology, 8(1). https://doi.org/10.1186/1471-2148-8-80