Analysis of genetic diversity in Brown Swiss, Jersey and Holstein populations using genome-wide single nucleotide polymorphism markers

BMC Research Notes

Flavio S Schenkel¹  Melkaye G Melka¹ 

[1] Centre for Genetic Improvement of Livestock, Department of Animal and Poultry Science, University of Guelph, 50 Stone Road East, Ontario, N1G 2W1, Canada

关键词: Genome-wide;    SNPs;    Genetic diversity;   

Others  :  1166557
DOI  :  10.1186/1756-0500-5-161

 received in 2011-10-21, accepted in 2012-03-22,  发布年份 2012

【 摘 要 】

Background

Studies of genetic diversity are essential in understanding the extent of differentiation between breeds, and in designing successful diversity conservation strategies. The objective of this study was to evaluate the level of genetic diversity within and between North American Brown Swiss (BS, n = 900), Jersey (JE, n = 2,922) and Holstein (HO, n = 3,535) cattle, using genotyped bulls. GENEPOP and FSTAT software were used to evaluate the level of genetic diversity within each breed and between each pair of the three breeds based on genome-wide SNP markers (n = 50,972).

Results

Hardy-Weinberg equilibrium (HWE) exact test within breeds showed a significant deviation from equilibrium within each population (P < 0.01), which could be a result of selection, genetic drift and inbreeding within each breed. Hardy-Weinberg test also confirmed significant heterozygote deficit in each breed over several loci. Moreover, results from population differentiation tests showed that the majority of loci have alleles or genotypes drawn from different distributions in each breed. Average gene diversity, expressed in terms of observed heterozygosity, over all loci in BS, JE and HO was 0.27, 0.26 and 0.31, respectively. The proportion of genetic diversity due to allele frequency differences among breeds (F_st) indicated that the combination of BS and HO in an ideally amalgamated population had higher genetic diversity than the other pairs of breeds.

Conclusion

Results suggest that the three bull populations have substantially different gene pools. BS and HO show the largest gene differentiation and jointly the highest total expected gene diversity compared to when JE is considered. If the loss of genetic diversity within breeds worsens in the future, the use of crossbreeding might be an option to recover genetic diversity, especially for the breeds with small population size.

【 授权许可】

   
2012 Melka and Schenkel; BioMed Central Ltd.

【 图 表 】

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