Chicken domestication: from archeology to genomics.

Current knowledge on chicken domestication is reviewed on the basis of archaeological, historical and molecular data. Several domestication centres have been identified in South and South-East Asia. Gallus gallus is the major ancestor species, but Gallus sonneratii has also contributed to the genetic make-up of the domestic chicken. Genetic diversity is now distributed among traditional populations, standardized breeds and highly selected lines. Knowing the genome sequence has accelerated the identification of causal mutations determining major morphological differences between wild Gallus and domestic breeds. Comparative genome resequencing between Gallus and domestic chickens has identified 21 selective sweeps, one involving a non-synonymous mutation in the TSHR gene, which functional consequences remain to be explored. The resequencing approach could also identify candidate genes responsible of quantitative traits loci (QTL) effects in selected lines. Genomics is opening new ways to understand major switches that took place during domestication and subsequent selection.