隨著大型跨國(guó)家禽公司的增長(zhǎng),，更少的商業(yè)品種的雞產(chǎn)生了全世界消費(fèi)的幾乎全部雞肉和雞蛋,。Hans Cheng及其同事證實(shí)了品種的減少意味著雞的遺傳多樣性的減少。這組科學(xué)家比較了標(biāo)準(zhǔn)的禽類(lèi)品種和來(lái)自商業(yè)養(yǎng)殖者的品種的數(shù)千個(gè)稱(chēng)為單核苷酸多樣性（SNPs）的遺傳標(biāo)記,，結(jié)果發(fā)現(xiàn)商業(yè)雞群隨著時(shí)間的推移失去了超過(guò)半數(shù)遺傳多樣性,。
隨著當(dāng)代雞的生產(chǎn)變得越來(lái)越商業(yè)化，家禽業(yè)選出了產(chǎn)蛋或產(chǎn)肉能力強(qiáng)的特定品種,，形成了商業(yè)雞群的基礎(chǔ),。然后養(yǎng)殖者針對(duì)每一個(gè)品種選出想要的性狀從而優(yōu)化了這些特性，這進(jìn)一步影響了遺傳多樣性的程度,。這組科學(xué)家說(shuō),，更少數(shù)量的公司培育雞已經(jīng)進(jìn)一步減少了雞的多樣性并增大了生存下來(lái)的雞對(duì)疾病的易感性。這組作者提出,，通過(guò)讓商業(yè)品種的雞和土雞雜交繁殖,，或者與不同商業(yè)雞群的未滅絕的品種雜交繁殖，可以恢復(fù)多樣性,。相關(guān)論文發(fā)表在美國(guó)《國(guó)家科學(xué)院院刊》（PNAS）上,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS，doi: 10.1073/pnas.0806569105,，William M. Muir,， Hans H. Cheng
Genome-wide assessment of worldwide chicken SNP genetic diversity indicates significant absence of rare alleles in commercial breeds
William M. Muira, Gane Ka-Shu Wongb,c, Yong Zhangc, Jun Wangc, Martien A.M. Groenend, Richard P.M.A. Crooijmansd, Hendrik-Jan Megensd, Huanmin Zhange, Ron Okimotof, Addie Vereijkeng, Annemieke Jungeriusg, Gerard A.A. Albersg, Cindy Taylor Lawleyh, Mary E. Delanyi, Sean MacEacherne, and Hans H. Chenge,1
aDepartment of Animal Sciences, Purdue University, West Lafayette, IN 47907;
bUniversity of Alberta, Department of Biological Sciences and Department of Medicine, Edmonton, Alberta T6G 2E9, Canada;
cBeijing Institute of Genomics of Chinese Academy of Sciences, Beijing Genomics Institute, Beijing Proteomics Institute, Beijing 101300, China;
dAnimal Breeding and Genomics Centre, Wageningen University, 6709 PG Wageningen, The Netherlands;
eUnited States Department of Agriculture, Agricultural Research Service, Avian Disease and Oncology Laboratory, East Lansing, MI 48823;
fCobb-Vantress, Inc., Siloam Springs, AR 72761;
gHendrix Genetics, 5831 CK Boxmeer, The Netherlands;
Abstract
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. 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. The results indicate 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. As such, hypothetically combining stocks within a company could recover only preexisting within-breed variability, but not more rare ancestral alleles. We establish that SNP weights act as sentinels of biodiversity and provide an objective assessment of the strains that are most valuable for preserving genetic diversity. This is the first experimental analysis investigating the extant genetic diversity of virtually an entire agricultural commodity. The methods presented are the first to characterize biodiversity in terms of allelic diversity and to objectively link rate of allele loss with the inbreeding coefficient.
