Copy number variation in the genomes of domestic animals.

Copy number variation (CNV) might be one of the main contributors to phenotypic diversity and evolutionary adaptation in animals and plants, employing a wide variety of mechanisms, such as gene dosage and transcript structure alterations, to modulate organismal plasticity. In the past 4 years, considerable advances have been made in the characterization of the genomic architecture of CNV in domestic species. First, low-resolution CNV maps were produced for cattle, goat, sheep, pig, dog, chicken, duck and turkey, showing that these structural polymorphisms comprise a significant part of these genomes. Furthermore, CNVs have been associated with several pigmentation (white coat in horse, pig and sheep) and morphological (late feathering and pea comb in chicken) traits, as well as with susceptibility to a wide array of diseases and developmental disorders, for example osteopetrosis, anhidrotic ectodermal dysplasia, copper toxicosis, intersexuality, cone degeneration, periodic fever and dermoid sinus, among others. In the future, development of high-resolution tools for CNV detection and typing combined with the implementation of databases integrating CNV, QTL and gene expression data will be essential to identify and measure the impact of this source of structural variation on the many phenotypes that are relevant to animal breeders and veterinary practitioners.