**5.1 Gene conversion**

Gene conversion describes the process by which the sequence content of one genetic locus is used as a template to alter and "paste over" the genetic sequence at a distal location. Gene conversion has the potential to enforce similarity across duplicate loci, both in terms of regulation and structure. A recent study on duplicated segments in a pair of *Drosophila* species made noted several anomalies that were suggestive of gene conversion. Interestingly, the edges of duplicated regions accumulated distinguishing mutations faster than more central regions, suggesting that these regions were being maintained by gene conversion and that the size of the region being converted was gradually being reduced by sequence mutations near the borders. Furthermore, paralogs near the boundaries of duplicated segments showed more divergence than those located near the centre (Osada & Innan, 2008). The authors note that this phenomenon could result in misleading estimates of synonymous divergence, as the conversion process would periodically homogenize the two sequences.

The requirements for a neofunctionalized gene to escape gene conversion and achieve fixation have been studied from a population genetics perspective (Teshima & Innan, 2008). The fit of the model is tested on a pair of human opsins, which differ in their light sensitivity.

Additional evidence that gene conversion may play a role in duplicate divergence was found in a study of WGD duplicates in rice. Duplicates that contained subsequences of particularly high sequence similarity also showed a tendency towards retaining similar regulation profiles. The authors suggest that this was a consequence of the promoter regions being propagated via gene conversion activity acting on the locally similar subsequences (Yim et al., 2009).
