Duplications of the genome that result in 'polyploid' organisms seem to be responsible for more plant-speciation events than was thought.
Troy Wood of the University of Münster in Germany and his colleagues have used existing genetic data on vascular plants to establish the frequency of speciation events in which an increase in ploidy — the number of copies of the genome — occurred. They find that 15% of angiosperms and almost one-third of fern species are derived from a polyploid event that may have rendered a plant morphologically distinct from and sexually incompatible with its former brethren. This is four times higher than previous estimates and, the authors say, may still be a conservative figure.
Although polyploidy seems to play an important part in creating new species, the team found no evidence that these polyploid plant lines go on to diversify more often than non-polyploids.
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Speciation: Multiplying effects. Nature 460, 782–783 (2009). https://doi.org/10.1038/460782e