Meeting Abstract
DNA-based analyses hold the promise of bringing repeatability and objectivity to the process of species delimitation, with the caveat that DNA-based delimitation decisions should be limited to instances where multiple types of analysis provide a coherent picture. The morphologically defined species Ravinia anxia and R. querula (Diptera:Sarcophagidae) have a long history of fluid (and even erroneous) species definitions and, thus, seem a logical candidate for application of DNA-based approaches. We examined DNA sequence data from two regions of the mitochondrial genome plus fragments of five different nuclear protein-coding genes, sampled from 30 individuals from across much of the geographic range of the two morphological species. Population genetic and phylogenetic approaches, including both discovery-based and validation-based methods, all agreed on the presence of three highly distinct evolutionary lineages. One lineage included only flies morphologically assigned to R. anxia and one included only flies morphologically assigned to R. querula. The third lineage, however, included flies morphologically assigned to both R. anxia and R. querula. Careful follow-up morphological examination of the specimens from the “mixed” lineage both reaffirmed the original species assignments and failed to discover any morphological feature uniquely shared by members of the mixed lineage. We thus conclude (for now) that the DNA-based species delimitation approaches may be capturing some retained ancestral polymorphisms, and that the two-species morphological definitions should be retained.
