Evolutionary toxicogenomics: diversification of the Cyp12d1 and Cyp12d3 genes in Drosophila species.

Gene duplication and divergence are overwhelmingly considered to be the primary mechanisms by which cytochrome P450 monooxygenases (P450s) have radiated into a large and diverse gene superfamily. To address how environmental stress drives the fixation and diversification of gene duplications, we have analyzed Cyp12d1 and Cyp12d3, a pair of duplicated genes found in the sequenced Drosophila genomes of the melanogaster group. The paralog Cyp12d3, which is not found in Drosophila melanogaster, is basal to the melanogaster group, after it split from the obscura group (ca.