William Atkins
Monday, 17 November 2008 22:16
Science -
Biology
Page 2 of 3
Their November 3, 2008 article “
Genome-wide assessment of worldwide chicken SNP genetic diversity indicates significant absence of rare alleles in commercial breeds” is published in the journal
Proceedings of the National Academy of Sciences (PNAS).
Its authors are William M. Muir (Purdue University, U.S.A.), Gane Ka-Shu Wong (University of Alberta, Canada), Yong Zhang and Jun Wang (Beijing Proteomics Institute, China), Martien A. M. Groenen, Richard P.M.A. Grooijmans, and Hendrik-Jan Megens (Wageningen University, The Netherlands), Huanmin Zhang, Sean MacEachern, and Hans H. Cheng (U.S. Department of Agriculture, U.S.A.), Ron Okimoto (Cobb-Vantress, Inc., U.S.A.), Addie Vereijken, Annemieke Jungerius, and Gerard A. A. Albers (Hendrix Genetics, The Netherlands), Cindy Taylor Lawley (Illumina, U.S.A.), and Mary E. Delany (University of California-Davis, U.S.A.),
They state in the abstract to their paper that,
“Breed utilization, genetic improvement, and industry consolidation are predicted to have major impacts on the genetic composition of commercial chickens. Consequently, the question arises as to whether sufficient genetic diversity remains within industry stocks to address future needs.”
Their methods included,
“With the chicken genome sequence and more than 2.8 million single-nucleotide polymorphisms (SNPs), it is now possible to address biodiversity using a previously unattainable metric: missing alleles. To achieve this assessment, 2551 informative SNPs were genotyped on 2580 individuals, including 1440 commercial birds."
"The proportion of alleles lacking in commercial populations was assessed by (1) estimating the global SNP allele frequency distribution from a hypothetical ancestral population as a reference, then determining the portion of the distribution lost, and then (2) determining the relationship between allele loss and the inbreeding coefficient.”
They found that
“… 50% or more of the genetic diversity in ancestral breeds is absent in commercial pure lines. The missing genetic diversity resulted from the limited number of incorporated breeds.”
In fact, chickens bred for their meat share over 30% of their genes. Some laying hens share up to 90% of their genes. Such percentages make the lines very susceptible to diseases.
Page three concludes the story.
