The Luxi gamecock developed very unique morphological and behavioral features under the special artificial selection of the most famous Chinese gamecocks. There are very few research studies on the genetics and selection of the Luxi gamecock. We used six methods (Fst, Tajima's D, hapFLK, iHS, XP-EHH, and Runs of homozygosity) to detect selective sweeps in whole-genome resequencing data of 19 Luxi gamecocks compared to other Chinese indigenous chickens. Eleven genes that were highly related to nervous system development (CDH18, SLITRK1, SLITRK6, NDST3, ATP23, LRIG3, IL1RAPL1, GADL1, C5orf22, UGT8, WISP1, and WNT9A) appeared in at least four methods and were regarded as the most significant genes under selection. Differentially expressed gene (DEG) analysis based on the RNA sequencing data of the cerebral cortex and middle brain between six Luxi gamecocks, Tibetan chickens, and white leghorns found that most differentially expressed genes were enriched in pathways with nervous system functions. Genes associated with aggressiveness-related neurotransmitters (SLC4A2, DRD1, DRD2, ADRA2A, and ADRA2B) showed differential expression rates in Luxi gamecocks as well. Combined results showed that most genes in selective sweep regions were also differentially expressed in Luxi gamecocks including the most significant genes (SLITRK6, IL1RAPL1, GADL1, WISP1, and LRIG3). This study provides more insight into molecular mechanisms of the aggressiveness of gamecocks and aims to promote further studies on animal and human aggression.
Keywords: RNA sequencing; cerebral cortex; midbrain; nervous system; selection signature; whole-genome resequencing.