Variation in the fitness impact of translationally optimal codons among animals

Relationship between N_e and translational selection (TS) intensity. Relationship between the population-scaled selection coefficient (S) and longevity (A), body length (B), d_N/d_S (C), and (D; N = 223 species). The TS intensity S is measured on the top 2% most highly expressed genes (S^hx). Pagel's lambda model is used to take into account the phylogenetic structure of the data in a regression model (the regression line is displayed in black when the correlation is significant). Error bars represent the 2.5th and 97.5th percentiles of S^hx values obtained by bootstraping (1000 draws with replacement among the top 2% most highly expressed genes, and the 50% least expressed).