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Free keywords:
evolution; gene expression; population divergence; wild mice
Abstract:
Divergence of gene expression is known to contribute to the differentiation and
separation of populations and species, although the dynamics of this process in
early stages of population divergence remains unclear. We analyzed gene
expression differences in three organs (brain, liver, and testis) between two natural
populations of Mus musculus domesticus that have been separated for at
most 3000 years. We used two different microarray platforms to corroborate
the results at a large scale and identified hundreds of genes with significant
expression differences between the populations. We find that although the three
tissues have similar number of differentially expressed genes, brain and liver
have more tissue–specific genes than testis. Most genes show changes in a single
tissue only, even when expressed in all tissues, supporting the notion that tissue
–specific enhancers act as separable targets of evolution. In terms of functional
categories, in brain and to a smaller extent in liver, we find transcription factors
and their targets to be particularly variable between populations, similar to previous
findings in primates. Testis, however, has a different set of differently
expressed genes, both with respect to functional categories and overall correlation
with the other tissues, the latter indicating that gene expression divergence
of potential importance might be present in other datasets where no differences
in fraction of differentially expressed genes were reported. Our results show that
a significant amount of gene expression divergence quickly accumulates
between allopatric populations.
