查看文章

There is good evidence that natural selection drives the evolution of locomotor performance, but the processes that generate the among-individual variation for selection to act on are relatively poorly understood. We measured prolonged swimming performance, U_crit, and morphology in a large cohort (n=461) of wild-type zebrafish (Danio rerio) at ∼6 months and again at ∼9 months. Using mixed-model analyses to estimate repeatability as the intraclass correlation coefficient, we determined that U_crit was significantly repeatable (r=0.55; 95% CI: 0.45–0.64). Performance differences between the sexes (males 12% faster than females) and changes with age (decreasing 0.07% per day) both contributed to variation in U_crit and, therefore, the repeatability estimate. Accounting for mean differences between sexes within the model decreased the estimate of U_crit repeatability to 21% below the naïve estimate …