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J Evol Biol. 2015 April; v.28 (4): 756–765. doi: 10.1111/jeb.12618


The evolution of multicellularity is a major transition that is not yet fully understood. Specifically, we do not know whether there are any mechanisms by which multicellularity can be maintained without a single-cell bottleneck or other relatedness-enhancing mechanisms. Under low relatedness, cheaters can evolve that benefit from the altruistic behaviour of others without themselves sacrificing. If these are obligate cheaters, incapable of cooperating, their spread can lead to the demise of multicellularity. One possibility, however, is that cooperators can evolve resistance to cheaters. We tested this idea in a facultatively multicellular social amoeba, Dictyostelium discoideum. This amoeba usually exists as a single cell but, when stressed, thousands of cells aggregate to form a multicellular organism in which some of the cells sacrifice for the good of others. We used lineages that had undergone experimental evolution at very low relatedness, during which time obligate cheaters evolved. Unlike earlier experiments, which found resistance to cheaters that were prevented from evolving, we competed cheaters and noncheaters that evolved together, and cheaters with their ancestors. We found that noncheaters can evolve resistance to cheating before cheating sweeps through the population and multicellularity is lost. Our results provide insight into cheater-resister coevolutionary dynamics, in turn providing experimental evidence for the maintenance of at least a simple form of multicellularity by means other than high relatedness.


This is the final author manuscript version of article published in Journal of Evolutionary Biology, v.28 (4): 756–765, April 2015. DOI 10.1111/jeb.12618

© 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology

Data is deposited at Dryad: doi:10.5061/dryad.80t07

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jeb12618-sup-0001-supinfo.xlsx (49 kB)
Appendix S1 Supplementary data for concurrent coevolution of intra-organismal cheaters and resisters.