Duffy MA, Brassil CE, Hall SR, Tessier AJ, Cáceres CE, Conner JK. Parasite-mediated disruptive selection in a natural Daphnia population.
BMC Evol Biol 2008;
8:80. [PMID:
18328099 PMCID:
PMC2276202 DOI:
10.1186/1471-2148-8-80]
[Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Accepted: 03/07/2008] [Indexed: 11/29/2022] Open
Abstract
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.
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