Figure 4. Historical and contemporary morphological differences between West and Central Africa rainforest populations of A. virens.

Regional populations are more morphologically divergent now than they were historically, due to West African populations becoming more ecotone-like as a result of deforestation. Error bars indicate ±1 SE about the mean; sample sizes area adjacent to error bars. PC1 is based upon tarsus, wing, tail, and upper mandible length, and to facilitate visualization are normalized, within time period, by the largest individual value so that PCs scale from −1 to +1. Measurements of individual traits are in millimeters. Significant Wilcoxon rank sums tests comparing regions within each time interval are indicated by ** and ***, denoting p≤0.01 and p≤0.001, respectively.