highly significantP < 1 × 10 −6
Although this pattern is consistent with the expectation that more functionally important genes (i.e., those that are more highly expressed) will exhibit reduced rates of introgression, these effects explained a negligible proportion of the variance (R 2 < 0.01 for both Asian and European data sets), and the relationship between mitochondrial targeting and introgression remained highly significant after controlling for this measure of transcript abundance ( P < 1 × 10 −6 in both Asian and European data sets).