Gene duplication and gene conversion in the Caenorhabditis elegans genome.

A comprehensive analysis of duplication and gene conversion for 7394 Caenorhabditis elegans genes (about half the expected total for the genome) is presented. Of the genes examined, 40% are involved in duplicated gene pairs. Intrachromosomal or cis gene duplications occur approximately two times more often than expected. In general the closer the members of duplicated gene pairs are, the more likely it is that gene orientation is conserved. Gene conversion events are detectable between only 2% of the duplicated pairs. Even given the excesses of cis duplications, there is an excess of gene conversion events between cis duplicated pairs on every chromosome except the X chromosome. The relative rates of cis and trans gene conversion and the negative correlation between conversion frequency and DNA sequence divergence for unconverted regions of converted pairs are consistent with previous experimental studies in yeast. Three recent, regional duplications, each spanning three genes are described. All three have already undergone substantial deletions spanning hundreds of base pairs. The relative rates of duplication and deletion may contribute to the compactness of the C. elegans genome.