Sequence conservation increases with mRNA expression ratio. Genes are binned by rank expression ratio: all genes, top 10%, 1%, and 0.1% most highly expressed. Amino acid sequence identity is averaged across all DNA reads per gene (HSP alignment regions only), and then across all genes per bin. Error bars are 95% confidence intervals.
Stewart et al. Genome Biology 2011 12:R26 doi:10.1186/gb-2011-12-3-r26