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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DNA helps sort out really big animals, crowding Ark

How many giraffes were onboard the Ark?  Giraffes are classified as a single species, Giraffa camelopardalis, with five to nine subspecies proposed based on regional variation in pelage (coat pattern). In 21 dec 2007 BMC Biology (open access) researchers from University of California, Los Angeles; Center for Conservation Research, Omaha Zoo; and Mpala Research Centre, Kenya, investigate genetic variation in giraffes across African continent. 

Using biopsy darts, the authors collected skin specimens from 266 giraffes at 19 localities in West, East, and South Africa. A 654 nucleotide region of mtDNA spanning cytb and control sequences was analyzed, revealing 35 haplotypes, and the remainder of the cytb gene (1709 bp total) was sequenced from one individual from each of the 35 haplotypes. The mtDNA sequences clustered into six reciprocally monophyletic lineages, which corresponded to groupings according to pelage pattern and regional location, and were largely concordant with subspecies designations.  Genetic distances suggested these groups have been reproductively isolated for 0.3 to 1.6 MY, similar to calculated divergence times among other closely-related mammals.

Analysis of 14 nuclear microsatellites from 381 individuals at 18 locations (it is not clear whether these are the same individuals as above) recovered the same six groups and suggested additional genetic subdivisions within some groups. Although at least some of the genetically and pelage-defined clusters have overlapping or adjacent ranges without geographic barriers, only three (0.8%) of individuals were identified as hybrids. These findings raise interesting questions about giraffe biology; for example, is there behavioral isolation perhaps based on visual recognition of pelage patterns? 

It is impressive that species can be overlooked in such large, boldly patterned, iconic animals.  Might there be similar divisions within the numerous species of small, brown, rarely seen mammals? Routine DNA analysis of a standardized mtDNA region (aka DNA barcoding) will help discover how finely divided animal biodiversity is.  Wilson and Reeder’s Mammal Species of the World, Third Edition lists 5,419 species, so this appears to be an achievable goal for our mammalian kin (list available online  I hope the authors include barcode region COI in their next analyses, so their data can be easily combined with other data sets, including the 28,560 mammalian barcode records in BOLD to date. 

This entry was posted on Friday, June 13th, 2008 at 7:42 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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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.