The evolution of gene expression levels in mammalian organs

Genome analyses can uncover protein-coding changes that potentially underlie the differences between species, but many of the phenotypic differences between species are the result of regulatory mutations affecting gene expression. Brawand et al. use high-throughput RNA sequencing to study the evolutionary dynamics of mammalian transcriptomes in six major tissues (cortex, cerebellum, heart, kidney, liver and testis) from ten species from all major mammalian lineages. Among the findings is the extent of transcriptome variation between organs and species, as well as the identification of potentially selectively driven expression switches that may have shaped specific organ biology.