Answers are grounded in this paper and cite their sources.
Jennifer M. Gleason, Elizabeth C. Griffith, Jeffrey R. Powell, A Molecular Phylogeny of the Drosophila willistoni Group: Conflicts Between Species Concepts?, Evolution, Vol. 52, No. 4 (Aug., 1998), pp. 1093-1103
No takes yet. Share an insight, caveat, or question.
Gleason et al. (1998) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: