Figure 4

Average allele lengths of FCA homologs shift with island age in the Hawaiian chain. Longer alleles are more frequent on younger islands. The mean differences are statistically significant (Kruskal-Wallis and ANOVA, P < 0.001). See Table 1 for island-island Tamhane's tests. X-axis, island age (in millions of years, decreasing, as indicated next to representative volcanoes [12]). Whiskers indicate ± 0.5 standard deviations around the means.