Expression variability following gene duplication facilitates gene retention

Genome analyses reveal that gene duplication in eukaryotes is pervasive, providing a primary source for the emergence of new genes. However, the mechanisms dictating early duplicate retention and the emergence of functional biases--such as the enrichment of tandem duplicates in environmental responses--remain unclear. Here, to better understand the mechanisms and factors determining gene retention, we study a frequently overlooked molecular feature--expression variability--as measured by within-line expression variation, termed variability. We demonstrate that, on average, genes with duplicates exhibit higher expression variability than singletons. Furthermore, small-scale duplications (SSDs) and whole-genome duplications (WGDs) display contrasting functional outcomes and time-dependent profiles in expression variability. These findings suggest a potential overarching mechanism that facilitates gene expression divergence, functional gains of environmental responses, and duplicate retention following SSDs.