Quantitative trait loci (QTL) and genetic parameters for economically important traits in chicken – A review

The study was aimed at reviewing and summarization of previous findings on associated genomic loci and estimated genetic parameters for reproductive traits in chicken. It was approached by reviewing various journals, books, genome database and used various genome browsing tools to collect the required information. Most of the reviewed information sources indicated that reproductive traits in chicken are genetically correlated, have low heritability and are affected by several quantitative trait loci (QTLs) that are located either on the same or different chromosomes. Both autosomal and sex chromosomes had influence on those traits. The majority of the reviewed QTLs had big confidence intervals and carries several candidate genes for the studied traits. Fine mapping using advanced intercross lines can help to narrow down the confidence intervals and target major genes. The information provided in this article, can contribute to our understanding of the complex inheritance pattern of the traits underlying reproductive performance in chicken

Reconstructing the origin and dispersal patterns of village chickens across East Africa: insights from autosomal markers

Unravelling the genetic history of any livestock species is central to understanding the origin, development and expansion of agricultural societies and economies. Domestic village chickens are widespread in Africa. Their close association with, and reliance on, humans for long-range dispersal makes the species an important biological marker in tracking cultural and trading contacts between human societies and civilizations across time. Archaezoological and linguistic evidence suggest a complex history of arrival and dispersion of the species on the continent, with mitochondrial DNA (mtDNA) D-loop analysis revealing the presence of five distinct haplogroups in East African village chickens. It supports the importance of the region in understanding the history of the species and indirectly of human interactions. Here, through a detailed analysis of 30 autosomal microsatellite markers genotyped in 657 village chickens from four East African countries (Kenya, Uganda, Ethiopia and Sudan), we identify three distinct autosomal gene pools (I, II and III). Gene pool I is predominantly found in Ethiopia and Sudan, while II and III occur in both Kenya and Uganda. A gradient of admixture for gene pools II and III between the Kenyan coast and Uganda's hinterland (P = 0.001) is observed, while gene pool I is clearly separated from the other two. We propose that these three gene pools represent genetic signatures of separate events in the history of the continent that relate to the arrival and dispersal of village chickens and humans across the region. Our results provide new insights on the history of chicken husbandry which has been shaped by terrestrial and maritime contacts between ancient and modern civilizations in Asia and East Africa