Figure 2: Fitness and body mass in the Maltese reed warbler population.
From: Rapid adaptive phenotypic change following colonization of a newly restored habitat
(a) Linear regression of mean population fitness (proportion of breeding adults each year (N years=16)) against the yearly distance from the adaptive optimum for body mass (θ) estimated from the OU model. As the population evolved towards the optimum, the mean population fitness increased significantly (linear regression: P=0.009) and overall, 58.7% of the variation in mean population fitness can be explained by variation in the distance from the adaptive optimum for body mass. (b) The effect of body mass on survival. Individuals marked and recaptured have a significantly lower body mass than individuals that are marked but never recaptured (total N=198). The dashed line corresponds to the adaptive optimum (θ) for body mass estimated from the OU model. The mean-standardized selection gradient is equal to −0.39 (linear regression: P=0.006).
