Asexual Amoebae Escape Muller's Ratchet through Polyploidy.
While some amoebae reproduce sexually, many amoebae (e.g., Acanthamoeba, Naegleria) reproduce asexually and therefore, according to popular doctrine, are likely to have been genetically disadvantaged as a consequence. In the absence of sex, mutations are proposed to accumulate by a mechanism known as Muller's ratchet. I hypothesise that amoebae can escape the ravages of accumulated mutation by virtue of their being polyploid. The polyploid state reduces spontaneous mutation accumulation by gene conversion, the freshly mutated copy being corrected by the presence of the many other wild-type copies. In this manner these amoebae reap the benefits of an asexual reproductive existence: principally, that it is rapid and convenient. Evidence for this mechanism comes from polyploid plants, bacteria, and archaea.
Centre for Integrative Physiology, Biomedical Sciences, Edinburgh Medical School, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK. Electronic address: smaciver@ed.ac.uk.
Sutherland K
SK
Maciver
D000656:Amoeba / Q000235:genetics*; D005785:Gene Conversion; D009154:Mutation / Q000235:genetics; D011123:Polyploidy; D012100:Reproduction, Asexual
Acanthamoeba; Entamoeba; Haldane's dilemma; Naegleria; evolution; gene conversion; homologous recombination