Beckenbach AT, Wei YW, Liu H.

Mol Biol Evol. 1993 May;10(3):619-34 doi:10.1093/oxfordjournals.molbev.a040034

Relationships in the Drosophila obscura species group, inferred from mitochondrial cytochrome oxidase II sequences.

Analysis of Cox2 sequences of Drosophila species is most compatible with a speciation of D. melanogaster and D. pseudoobscura ~35 My ago. Sequence divergence between D. mel. and members of the D. obscura species group is in average of 11.4 %.