Figure 2. Gene variance independent of expression is correlated across species.
(A) To estimate dispersion, RNA-seq counts for 39 human heart tissue samples were used to estimate gene-wise mean (μ) and overdispersion (ϕ) parameters. Across all genes, overdispersion is correlated with mean expression (left) in the hexbin scatter plot. We regressed out this correlation, using the residual of a LOESS fitted line (blue) as a metric (dispersion) of the variability of a gene’s expression across a population relative to similarly expressed genes (a.u., arbitrary units). (B) Dispersion estimates and the underlying expression in each sample for three similarly expressed genes in human and chimpanzee. Error bars represent bootstrapped standard error. Q-value for ZNF514 represents an estimate of FDR after genome-wide multiple hypothesis testing correction. (C) Dispersion estimates across all genes are correlated across human and chimpanzee, despite identification of thousands of differentially dispersed genes in red. R and p-value correspond to Pearson’s correlation. Full dispersion estimates and differential dispersion results available as Figure 2—source data 1.
Figure 2—figure supplement 1. Interspecies dispersion estimates are largely independent from interspecies mean expression changes.
