Adh and Adh-dup sequences of Drosophila lebanonensis and D. immigrans: interspecies comparisons

We have cloned and sequenced the Adh genomic region of Drosophila lebanonensis (subgenus Scaptodrosophila) and D. immigrans (subgenus Drosophila). This region, which contains Adh, encoding the alcohol dehydrogenase enzyme, and Adh-dup (duplicate of Adh), has been compared with the same fragment from D. subobscura (subgenus Sophophora). Even though the flanking regions and introns of both genes have been affected by high substitution rates, the consensus sequences have been clearly identified. Although the overall homology of the coding regions was 76-78% among the species compared, there were differences in the exon distribution of the nucleotide substitutions when Adh or Adh-dup were compared, thus showing that these two genes differ in their evolutionary pattern.