The evolution of reduced antagonism – A role for host-parasite coevolution

• Type of Material: Article
• Authors: AK Gibson, Indiana University; KS Stoy, Indiana University; IA Gelarden, Indiana University; MJ Penley, Emory University; CM Lively, Indiana University; Levi Morran, Emory University
• Language: English
• Date: 2015-11-01
• Publisher: Wiley
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2015, Society for the Study of Evolution.
• Final Published Version (URL): http://dx.doi.org/10.1111/evo.12785
• Title of Journal or Parent Work: Evolution
• ISSN: 0014-3820
• Volume: 69
• Issue: 11
• Start Page: 2820
• End Page: 2830
• Grant/Funding Information: Funding was provided by the National Institutes of Health (1F32GM096482-01 to LTM; IU Common Themes in Reproductive Diversity training grant to AKG), the National Science Foundation (Graduate Research Fellowship to AKG), and the IU Hutton Honors College (Research Grant to KSS).
• Keywords: TRANSMISSION; SYSTEM; Environmental Sciences & Ecology; LOCAL ADAPTATION; experimental coevolution; Ecology; evolution of virulence; Evolutionary Biology; Science & Technology; Genetics & Heredity; SPECIES INTERACTIONS; experimental evolution; Caenorhabditis elegans; MUTUALISM; Life Sciences & Biomedicine; Serratia marcescens
• Research Categories: Biology, Ecology; Biology, Parasitology

Abstract

Why do some host-parasite interactions become less antagonistic over evolutionary time? Vertical transmission can select for reduced antagonism. Vertical transmission also promotes coevolution between hosts and parasites. Therefore, we hypothesized that coevolution itself may underlie transitions to reduced antagonism. To test the coevolution hypothesis, we selected for reduced antagonism between the host Caenorhabditis elegans and its parasite Serratia marcescens. This parasite is horizontally transmitted, which allowed us to study coevolution independently of vertical transmission. After 20 generations, we observed a response to selection when coevolution was possible: reduced antagonism evolved in the copassaged treatment. Reduced antagonism, however, did not evolve when hosts or parasites were independently selected without coevolution. In addition, we found strong local adaptation for reduced antagonism between replicate host/parasite lines in the copassaged treatment. Taken together, these results strongly suggest that coevolution was critical to the rapid evolution of reduced antagonism.