Nature. 2011 Oct 19;478(7369):343-8. doi: 10.1038/nature10532.

The evolution of gene expression levels in mammalian organs.

Brawand D, Soumillon M, Necsulea A, Julien P, Csárdi G, Harrigan P, Weier M,
Liechti A, Aximu-Petri A, Kircher M, Albert FW, Zeller U, Khaitovich P, Grützner
F, Bergmann S, Nielsen R, Pääbo S, Kaessmann H.

Center for Integrative Genomics, University of Lausanne, 1015 Lausanne,
Switzerland.

Changes in gene expression are thought to underlie many of the phenotypic
differences between species. However, large-scale analyses of gene expression
evolution were until recently prevented by technological limitations. Here we
report the sequencing of polyadenylated RNA from six organs across ten species
that represent all major mammalian lineages (placentals, marsupials and
monotremes) and birds (the evolutionary outgroup), with the goal of understanding
the dynamics of mammalian transcriptome evolution. We show that the rate of gene
expression evolution varies among organs, lineages and chromosomes, owing to
differences in selective pressures: transcriptome change was slow in nervous
tissues and rapid in testes, slower in rodents than in apes and monotremes, and
rapid for the X chromosome right after its formation. Although gene expression
evolution in mammals was strongly shaped by purifying selection, we identify
numerous potentially selectively driven expression switches, which occurred at
different rates across lineages and tissues and which probably contributed to the
specific organ biology of various mammals.

PMID: 22012392  [PubMed - in process]