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23 de julio de 2012

Will DNA Barcoding wreck the NCBI Genbank?

This recent paper (An update on DNA barcoding: low species coverage and numerous unidentified sequences; published in Cladistics) on an update of the Global DNA barcoding effort should be a real eye-opener to all people who love the NCBI Genbank and the process and openness of science, and especially to taxonomists.
....
So the paper published in cladistics, looks at the claims of these “barcoders” and find some problems. They check whether:
  1. This project lived up to its initial speech act? (species coverage problem)
  2. Is it progressing scientifically? (“taxonomy” wise is it 100% percent right?)
Well, the answers are in the negative.
They find ~60,000 “metazoa” species’ barcodes in the NCBI database, which is well below the number of 10-20 million total species on earth (some claims are less but see the link). This is despite having substantial funding from the governments for the barcoding initiative. This paper says that they (Barcoding consortium) received $80 million from the Canadian government, we know about many other sources where every small barcoder gets tens of millions.
....

In short, DNA barcoding has performed below par, and their quest to barcode all species has failed at least until now. The main problems could be that they did not have trained taxonomists in their ranks. They are against taxonomy using morphological identification, thus these taxonomists distance themselves from barcoding, and barcoders know little taxonomy to correctly identify a species to its specific level. If barcoders say that they found cryptic diversity that was deposited as “sp.” in databases, then why 1000 specimens (with <1% identity), and I would also ask those people to read better about species delimitation methods.

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16 de julio de 2012

DNA barcoding: mucho ruido ... pocas nueces .... muy ... muy caras!


Cladistics Early on line: An update on DNA barcoding: low species coverage and numerous unidentified sequences

Abstract

DNA barcoding was proposed in 2003, the Consortium for the Barcode of Life was established in 2004, and the movement has since attracted more than $80 million funding. Here we investigate how many species of multicellular animals have been barcoded. We compare the numbers in a public database (GenBank as of January 2012) with those in the Barcode of Life Database (BOLD) and find that GenBank contains COI (cytochrome c oxidase subunit 1) sequences for ca. 60 000 species while BOLD reports barcodes for ca. 150 000 species. The discrepancy is likely due to a large amount of unpublished data in BOLD. Overall, the species coverage remains sparse, growth rates are low, and the barcode accumulation curve for Metazoa is linear with only 4788 species having been added in 2011. In addition, the vast majority of species in the public database (73%) were barcoded by projects that are unlikely to be related to the DNA barcoding movement. Particularly surprising was the large number of DNA barcodes in GenBank that were not identified to species (Jan 2012: 74%), with insect barcodes often being identified only to order. Of these several hundred thousand have since been suppressed by NCBI because they did not satisfy the iBOL/GenBank early release agreement. Species coverage is considerably better for target taxa of DNA barcoding campaigns (e.g. birds, fishes, Lepidoptera), although it also falls short of published campaign targets.
© The Willi Hennig Society 2012

5 de julio de 2012

Tema de la semana‎ > ‎ Homoplasia: De bestia negra a caso valioso.

Homoplasia: De bestia negra a caso valioso

publicado a la‎(s)‎ 12/10/2011 06:36 por Martín Ramírez 

Tradicionalmente concebida como un problema para la sistemática, la homoplasia nos ofrece una oportunidad única de estudiar fenómenos históricos que de otra manera sería únicos.  Wake et al. (2011) presentan una revisión didáctica de la utilidad del estudio de convergencias y reversiones para comprender los mecanismos subyacentes a la evolución de la morfología.

Wake, D.B., Wake, M.H., Specht, C.D., 2011. Homoplasy: from detecting pattern to determining process and mechanism of evolution. Science 331, 1032-1035. [PDF]

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