BackgroundThe genetic basis of animal domestication remains poorly understood, and systems with substantial phenotypic differences between wild and domestic populations are useful for elucidating the genetic basis of adaptation to new environments as well as the genetic basis of rapid phenotypic change. Here, we sequenced the whole genome of 78 individual ducks, from two wild and seven domesticated populations, with an average sequencing depth of 6.42X per individual.ResultsOur population and demographic analyses indicate a complex history of domestication, with early selection for separate meat and egg lineages. Genomic comparison of wild to domesticated populations suggests that genes that affect brain and neuronal development have undergone strong positive selection during domestication. Our FST analysis also indicates that the duck white plumage is the result of selection at the melanogenesis-associated transcription factor locus.ConclusionsOur results advance the understanding of animal domestication and selection for complex phenotypic traits.

To trace the source of the avian H7N9 viruses, we collected 99 samples from 4 live poultry markets and the family farms of 3 patients in Hangzhou city of Zhejiang province, China. We found that almost all positive samples came from chickens and ducks in live poultry markets. These results strongly suggest that the live poultry markets are the major source of recent human infections with H7N9 in Hangzhou city, Zhejiang province of China. Therefore, control measures are needed, not only in the domestic bird population, but also in the live poultry markets to reduce human H7N9 infection risk.

Zhang et al. Genetic Structure Analysis of Populations the highest female-to-male ratios. Interestingly, RJF comprised a greater proportion of males than females. Our results show the population genetics of chickens under selection pressures, and can aid in the development of better conservation strategies for different chicken breeds.

The conservation and development of chicken have received considerable attention, but the admixture history of chicken breeds, especially Chinese indigenous breeds, has been poorly demonstrated. In this study, we aimed to evaluate the genetic diversity and population structure of eight chicken breeds (including conserved chicken breeds) from different geographic origin and to identify admixture within these breeds using a 600-K single-nucleotide polymorphism panel for genotyping. Using the genotype of 580,961 single-nucleotide polymorphism markers scored in 1,200 animals, we evaluated the genetic diversity (heterozygosity and proportion of polymorphic markers), linkage disequilibrium decay, population structure (principal component analysis and neighbor-joining tree), genetic differentiation (FST and genetic distance), and migration events (TreeMix and f-statistics) of the eight domesticated chicken breeds. The results of population analytical methods revealed patterns of hybridization that occurred after divergence in Tibetan chicken. We argue that chicken migration and admixture, followed by trade, have been important forces in shaping the genomic variation in modern Chinese chicken. Moreover, isolation by distance might play a critical role in shaping the genomic variation within Eurasia continent chicken breeds. Moreover, genetic information provided in this study is valuable resources for production applications (genomic prediction, and breeding strategy) and scientific research (genetic basis detection, studying evolution, or domestication).