The domesticated chicken, the bird for which the most genetic information is available. Its ancestor is the Asian red jungle fowl, from which it was domesticated around 8,000 bc. Its genome size is about 1 gbp and its number of protein coding genes is ∼23,000. Birds, snakes, and lizards have two classes of chromosomes: macrochromosomes and microchromosomes. In chickens there are 10 macrochromosomes and 29 microchromosomes. The fifth chromosome in length is the metacentric Z, which occurs in duplicate in males. The female has one Z and a smaller w chromosome. The macrochromosomes including the Z replicate synchronously. All the microchromosomes replicate late and so does the w of females. Roughly 60% of all the protein coding genes in the chicken have human orthologs. The haploid chromosome number is 39. The female is the heterogametic sex (ZW), whereas the male is the homogametic sex (ZZ). There are over 200 genes that have been mapped. Estimated genome size is 1.125 × 109 base pairs. See Classification, Chordata, Aves, Galliformes; comb shape, plumage pigmentation genes, poultry breeds.
Subjects: Genetics and Genomics.