Viruses and the termination of blooms
Scientists have named alternative models for the relationship between Emiliania huxleyi and the viruses that infect it ‘Red Queen evolutionary dynamics’ and ‘Cheshire Cat dynamics’, inspired by the behaviour of the characters in the book Alice in Wonderland.
Red Queen or Cheshire Cat?
A series of studies (for example, Bratbak et al. 1993, Martinez et al. 2007) have shown that towards the end of Emiliania huxleyi blooms the cells are infested by large viruses, termed E. huxleyi viruses. The build-up of these viruses kills the coccolithophores and ends the blooms.
It has been suggested that these viruses have helped drive the rapid evolution shown by E. huxleyi and closely related coccolithophores. This would be a classic case of Red Queen evolutionary dynamics (van Valen, 1973), named after the Red Queen in Alice in Wonderland who found, 'It takes all the running you can do, to keep in the same place'.
However, an elegant study by Frada et al. (2009) suggests an alternative model, which they named 'Cheshire Cat dynamics' after the cat in Alice in Wonderland which escaped execution by gradually turning invisible.
This study showed that the viruses only infect the diploid, coccolith-bearing, stage of the lifecycle. The alternate haploid stage of the life-cycle appears to be immune to the virus, possibly because it has a very different cell-surface and so is in effect invisible to the virus. The researchers speculated that at the end of blooms a proportion of the population escapes the viruses by switching to the alternate lifecycle phase.