Gene Loss and Evolution of Surviving Paralogs Figure 5. Conserved syntenies provide evidence that aldh1a1 was lost in stem teleosts. This analysis provides evidence that the genomic duplication that generated Aldh1a1 and Aldh1a2 from an ancestral Aldh1a1/2 gene predated the tetrapod-teleost divergence. Aldh1a gene family members are highlighted in red, and the nearest Aldh1a1 conserved syntenic genes are labeled in purple. Teleost-specific tmc tandem duplicates located in the position predicted for the lost aldh1a1 are brown. This analysis suggests that the loss of the aldh1a1 ortholog probably occurred before the teleost radiation, which rules out the hypothesis that Aldh1a1 is a tetrapod innovation. Additional paralogous clusters with low conserved synteny with the Hsa ALDH1A1 genomic neighborhood were found in secondary chromosomal regions in teleost genomes (e.g. Dre8, GacXIV, and Ola12; included in Table S3 and Figure S2). doi:10.1371/journal.pgen.1000496.g005 PLoS Genetics | www.plosgenetics.org 9 May 2009 | Volume 5 | Issue 5 | e1000496