Analyses of mitogenomic markers shed light on the divergence, population dynamics, and demographic history of Pakistani chickens

Pakistan is one of a few sites, associated with the earliest known independent domestication event in the evolutionary history of chicken, which is socio-economically and historically the most important poultry bird in the country. However, the divergence, past population dynamics, and demographic history of Pakistani chickens have not been addressed so far. Therefore, we herein investigated the indigenous Pakistani chickens using mitogenomic markers. We first prepared individual DNA samples from the chicken feathers, and generated nucleotide sequence data, which was then subjected to various population genetics analyses. In molecular phylogenetic analysis, the Pakistani chickens were clustered under nine different clades. Among the wild fowls, the Indian red jungle fowl (IRJF) shared very close affinities to Pakistani chickens. The Bayesian skyline plot showed an increase in the effective population size of Pakistani chickens during the last 50 years. Finally, a time-calibrated phylogeny inferred molecular divergence of the Pakistani chickens. A molecular rate of 3.6 x 10(-6) mutations/site/year (95% HPD interval: 2.28 x 10(-8) to 9.32 x 10(-6)) was estimated for the data set. In a rooted tree with root-age of 12058 years (95% HPD interval: 1161-38411), the Pakistani chicken haplotypes showed divergence from IRJF haplotypes around 6987 years (95% HPD interval: 1132-20746) ago, and they shared their most recent common ancestor with Gallus gallus spadiceus, and G. g. jabouillei at the root of the tree. Overall, these results suggest that Pakistani chicken haplotypes share their ancestral gene pool with the IRJF as compared to other red jungle fowl subspecies.

Automated summary

The study investigated indigenous Pakistani chickens using mitogenomic markers, revealing close affinities with Indian red jungle fowls and an increase in population size in the last 50 years. Time-calibrated phylogeny showed molecular divergence of Pakistani chickens around 6987 years ago.