The taxonomic rank of Spizella taverneri: A response to Mayr and Johnson

Mayr and Johnson suggest that Spizella taverneri should be a subspecies of the biological species S. breweri, because it is possibly not reproductively isolated. We originally concluded that evidence from mitochondrial DNA sequences, habitat preferences, timing of breeding, vocalizations, and morphology supported the recognition of S. taverneri as a phylogenetic and biological species. Nothing in the commentary by Mayr and Johnson causes us to change that conclusion. We believe that it is probable that these two allopatric taxa are isolated. Contrary to Mayr and Johnson, we believe that more information is given by ranking S. taverneri as a species, because it reveals the fact that they are independently evolving taxa. The classification of Spizella should convey the sister-species status of S. taverneri and S. breweri, without regard for balancing the degree of sequence divergence among species, as suggested by Mayr and Johnson.