Present address: Research and Development Division, Fumakilla Ltd., Hatsukaichi, Hiroshima, 739-0494, Japan.
Persistence of the single lineage of transmissible ‘social cancer’ in an asexual ant
Article first published online: 14 DEC 2010
© 2010 Blackwell Publishing Ltd
Volume 20, Issue 3, pages 441–455, February 2011
How to Cite
DOBATA, S., SASAKI, T., MORI, H., HASEGAWA, E., SHIMADA, M. and TSUJI, K. (2011), Persistence of the single lineage of transmissible ‘social cancer’ in an asexual ant. Molecular Ecology, 20: 441–455. doi: 10.1111/j.1365-294X.2010.04954.x
- Issue published online: 17 JAN 2011
- Article first published online: 14 DEC 2010
- Received 15 April 2010; revision received 17 October 2010; accepted 19 October 2010
- clonal genetic structure;
- Emery’s rule;
- evolution of cooperation;
- genetic caste determination;
- transmissible cancer
How cooperation can arise and persist, given the threat of cheating phenotypes, is a central problem in evolutionary biology, but the actual significance of cheating in natural populations is still poorly understood. Theories of social evolution predict that cheater lineages are evolutionarily short-lived. However, an exception comes from obligate socially parasitic species, some of which thought to have arisen as cheaters within cooperator colonies and then diverged through sympatric speciation. This process requires the cheater lineage to persist by avoiding rapid extinction that would result from the fact that the cheaters inflict fitness cost on their host. We examined whether this prerequisite is fulfilled, by estimating the persistence time of cheaters in a field population of the parthenogenetic ant Pristomyrmex punctatus. Population genetic analysis found that the cheaters belong to one monophyletic lineage which we infer has persisted for 200–9200 generations. We show that the cheaters migrate and are thus horizontally transmitted between colonies, a trait allowing the lineage to avoid rapid extinction with its host colony. Although horizontal transmission of disruptive cheaters has the potential to induce extinction of the entire population, such collapse is likely averted when there is spatially restricted migration in a structured population, a scenario that matches the observed isolation by distance pattern that we found. We compare our result with other examples of disruptive and horizontally transmissible cheater lineages in nature.