Rockefeller University

Program for the Human Environment

The Barcode Blog

A mostly scientific blog about short DNA sequences for species identification and discovery. I encourage your commentary. -- Mark Stoeckle

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Update: mtDNA clusters durable, congruent with nuclear markers

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.

 

This entry was posted on Friday, January 5th, 2007 at 8:19 pm and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

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Contact: mark.stoeckle@rockefeller.edu

About this site

This web site is an outgrowth of the Taxonomy, DNA, and Barcode of Life meeting held at Banbury Center, Cold Spring Harbor Laboratory, September 9-12, 2003. It is designed and managed by Mark Stoeckle, Perrin Meyer, and Jason Yung at the Program for the Human Environment (PHE) at The Rockefeller University.

About the Program for the Human Environment

The involvement of the Program for the Human Environment in DNA barcoding dates to Jesse Ausubel's attendance in February 2002 at a conference in Nova Scotia organized by the Canadian Center for Marine Biodiversity. At the conference, Paul Hebert presented for the first time his concept of large-scale DNA barcoding for species identification. Impressed by the potential for this technology to address difficult challenges in the Census of Marine Life, Jesse agreed with Paul on encouraging a conference to explore the contribution taxonomy and DNA could make to the Census as well as other large-scale terrestrial efforts. In his capacity as a Program Director of the Sloan Foundation, Jesse turned to the Banbury Conference Center of Cold Spring Harbor Laboratory, whose leader Jan Witkowski prepared a strong proposal to explore both the scientific reliability of barcoding and the processes that might bring it to broad application. Concurrently, PHE researcher Mark Stoeckle began to work with the Hebert lab on analytic studies of barcoding in birds. Our involvement in barcoding now takes 3 forms: assisting the organizational development of the Consortium for the Barcode of Life and the Barcode of Life Initiative; contributing to the scientific development of the field, especially by studies in birds, and contributing to public understanding of the science and technology of barcoding and its applications through improved visualization techniques and preparation of brochures and other broadly accessible means, including this website. While the Sloan Foundation continues to support CBOL through a grant to the Smithsonian Institution, it does not provide financial support for barcoding research itself or support to the PHE for its research in this field.