Fig. 4.

Heterogeneous genetic divergence along the B. stricta genome. a Manhattan plot of Z-transformed F_ST (Z-F_ST) in 20-kb non-overlapping windows for six group pairs. Alternating colors paint the different chromosomes, and the genomic islands of divergence are shown in red. Windows with low differentiation (Z-F_ST < 0) are not shown. The vertical lines (light blue) mark the three highly polymorphic genomic regions (see Fig. 3) that were not included in F_ST analyses. b) Kernel distribution of genome-wide differentiation (F_ST) for six group pairs. c Box plot of absolute divergence (d_XY). In each of the six group pairs, mean d_XY values in genomic islands (blue) are significantly higher than those in genomic background (red) (P < 10⁻⁵, randomization test). In these box plots, the median is shown by a horizontal line, while the bottom and top of each box represents the first and third quartiles. The whiskers extend to 1.5 times the interquartile range. Outliers are not shown in the plot