Abstract
We compared the nucleotide substitution pattern over the entire genome of two unique variants of the 6,300-bp selfish DNA (2 μm) plasmid in Saccharomyces cerevisiae. The DNA sequence of the left-unique region is identical among 2-μm variants, while the right-unique region shows substantial divergence. This chimeric pattern cannot be explained by neutral or Darwinian selection models. We propose that horizontal transmission of the 2-μm plasmid coupled with a directed, polarized gene conversion maintains the DNA sequence of the left-unique region, whereas the right-unique region is subject to random drift and Darwinian selection.
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Correspondence to: G.H. Rank
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Xie, Y., Pelcher, L.E. & Ranks, G.H. Chimeric evolution of the 2-μm genome in Saccharomyces cerevisiae . J Mol Evol 38, 363–368 (1994). https://doi.org/10.1007/BF00163153
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DOI: https://doi.org/10.1007/BF00163153