MicroRNA regulation and interspecific variation of gene expression.

MicroRNAs (miRNAs) modulate expression of their target genes in various tissues and at different developmental stages, but it is unclear whether they drive cross-species variation in gene expression. By comparing data from mammal and fly species we found that the cross-species expression variation of miRNA targets is significantly lower than that of other genes. This implies that miRNAs can affect gene expression by reducing stochastic noise, buffering cross-species variation and constraining evolutionary gene expression variation.