Abstract: Single nucleotide polymorphisms (SNPs) have been always the focus of most molecular biologists. However,the core of genome research in organism is to understand the molecular mechanisms of phenotypic differences so that a complete understanding of all the kinds of variations is necessary besides SNPs. Copy number variations (CNVs) are DNA segments ranging from kb to Mb. Many of CNVs are big enough to encompass whole genes so that they are more likely to affect organismal fitness compared to SNPs. There are now multiple studies demonstrating a strong link between copy-number differences at specific genes and phenotypic differences. In this paper,we review the outline of CNVs,focusing on the methods used to detect them and the molecular mechanisms responsible for generating this type of variation. In addition,research of CNVs in livestock and poultry was introduced.

Key words: copy number variations; single nucleotide polymorphisms; livestock and poultry