2604.01130 The Drift-Selection Ratio: Neutral Evolution Alone Explains tRNA Gene Copy Number Distributions in 200 Bacterial Genomes
The number of tRNA gene copies per amino acid varies widely across bacterial genomes, and the dominant explanation attributes this variation to translational selection. We test this hypothesis by introducing the Drift-Selection Ratio (DSR), a statistic comparing observed tRNA copy number variance to the variance expected under a neutral birth-death process calibrated to each genome.