A Comparison of Brain Gene Expression Levels in Domesticated and Wild Animals

Domestication has led to similar changes in morphology and behavior in several animal species, raising the questionwhether similarities between different domestication events also exist at the molecular level. We used mRNA sequencing toanalyze genome-wide gene expression patterns in brain frontal cortex in three pairs of domesticated and wild species (dogsand wolves, pigs and wild boars, and domesticated and wild rabbits). We compared the expression differences with thosebetween domesticated guinea pigs and a distant wild relative (Cavia aperea) as well as between two lines of rats selectedfor tameness or aggression towards humans. There were few gene expression differences between domesticated and wilddogs, pigs, and rabbits (30–75 genes (less than 1%) of expressed genes were differentially expressed), while guinea pigs andC. aperea differed more strongly. Almost no overlap was found between the genes with differential expression in thedifferent domestication events. In addition, joint analyses of all domesticated and wild samples provided only suggestiveevidence for the existence of a small group of genes that changed their expression in a similar fashion in differentdomesticated species. The most extreme of these shared expression changes include up-regulation in domesticates of SOX6and PROM1, two modulators of brain development. There was almost no overlap between gene expression in domesticatedanimals and the tame and aggressive rats. However, two of the genes with the strongest expression differences betweenthe rats (DLL3 and DHDH) were located in a genomic region associated with tameness and aggression, suggesting a role ininfluencing tameness. In summary, the majority of brain gene expression changes in domesticated animals are specific tothe given domestication event, suggesting that the causative variants of behavioral domestication traits may likewise bedifferent.funding agencies|Max Planck Society||European Research Council|233297|German Science Foundation (DFG)|AL 1525/1-1|CAS young scientists fellowship|2009Y2BS12|National Science Foundation of China research grant|31010022||SFRH/BPD/65464/2009|