Thousands of long intergenic noncoding RNAs (lincRNAs) have been identified in the human and mouse genomes, some of which play important roles in fundamental biological processes. The pig is an important domesticated animal, however, pig lincRNAs remain poorly characterized and it is unknown if they were involved in the domestication of the pig. Here, we used available RNA-seq resources derived from 93 samples and expressed sequence tag data sets, and identified 6,621 lincRNA transcripts from 4,515 gene loci. Among the identified lincRNAs, some lincRNA genes exhibit synteny and sequence conservation, including linc-sscg2561, whose gene neighbor Dnmt3a is associated with emotional behaviors. Both linc-sscg2561 and Dnmt3a show differential expression in the frontal cortex between domesticated pigs and wild boars, suggesting a possible role in pig domestication. This study provides the first comprehensive genome-wide analysis of pig lincRNAs.

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Animal domestication has far-reaching significance for human society. The sequenced genomes of domesticated animals provide critical resources for understanding the genetic basis of domestication. Various genomic analyses have shed a new light on the mechanism of artificial selection and have allowed the mapping of genes involved in important domestication traits. Here, we summarize the published genomes of domesticated animals that have been generated over the past decade, as well as their origins, from a phylogenomic point of view. This review provides a general description of the genomic features encountered under a two-stage domestication process. We also introduce recent findings for domestication traits based on results from genome-wide association studies and selective-sweep scans for artificially selected genomic regions. Particular attention is paid to issues relating to the costs of domestication and the convergent evolution of genes between domesticated animals and humans.

Tibetan pig is native to the Qinghai-Tibet Plateau and has adapted to the high-altitude environmental condition such as hypoxia. However, its origin and genetic mechanisms underlying high-altitude adaptation still remain controversial and enigmatic. Herein, we analyze 229 genomes of wild and domestic pigs from Eurasia, including 63 Tibetan pigs, and detect 49.6 million high-quality variants. Phylogenomic and structure analyses show that Tibetan pigs have a close relationship with low-land domestic pigs in China, implying a common domestication origin. Positively selected genes in Tibetan pigs involved in high-altitude physiology, such as hypoxia, cardiovascular systems, UV damage, DNA repair. Three of loci with strong signals of selection are associated with EPAS1 , CYP4F2 , and THSD7A genes, related to hypoxia and circulation. We validated four non-coding mutations nearby EPAS1 and CYP4F2 showing reduced transcriptional activity in Tibetan pigs. A high-frequency missense mutation is found in THSD7A (Lys561Arg) in Tibetan pigs. The selective sweeps in Tibetan pigs was found in association with selection against non-coding variants, indicating an important role of regulatory mutations in Tibetan pig evolution. This study is important in understanding the evolution of Tibetan pigs and advancing our knowledge on animal adaptation to high-altitude environments.