In early online J Zool Syst Evol Res researchers from Natural History Museum and Imperial College, London, scrutinize “recent advances in DNA taxonomy…that follow the dramatic increase in data generation“. Authors Vogler and Monaghan provide a scientific update to
what has been learned so far: “a key finding from recent studies in animals is that variation in mitochondrial DNA is partitioned as tight clusters of closely related genotypes, which group specimens largely according to traditionally recognized species limits, and which are congruent with nuclear markers”,
the durability of clustering: “it can be expected that denser geographic and taxonomic sampling may result in the discovery of new clusters, and perhaps reduce their divergence from each other, but they are unlikely to erode the clustering altogether”,
the significance of incongruence between DNA-based and morphology-based methods for delimiting species: “the high degree of congruence of mtDNA groups and traditionally defined taxa appears to contradict the reported mismatch of established species boundaries…even well-studied groups may be in need of taxonomic revision before accurate tests of incongruence can be conducted”,
what the future holds: “a standard DNA taxonomic analysis will include broad sampling..followed by large-scale sequencing, and algorithmic procedures for delineating species limits. The taxonomic system will be derived from the data rather than expert opinion“,
and what is needed to harness DNA taxonomy in general and DNA barcoding in particular to speed description of the estimated 80% of earth’s biodiversity that is at yet undescribed: “a feedback loop that [uses] discrepancies between DNA and other data to refine species descriptions..founded in existing theory of evolutionary biology and phylogenetics”
I close with a pictorial analogy. The Coulter counter uses electrical sensing to gain the same information as morphologic diagnosis of blood smears, with dramatic improvements in speed, cost, and necessary expertise. In some situations, DNA sequencing may provide similar improvements over morphologic diagnosis for species-level identification.