Fig. 4: Summary of the genomic cline analysis.

a The histogram depicts the distribution of hybrid indexes in the Dubois hybrid zone. b This plot shows estimated genomic clines for a subset of ancestry-informative SNPs (AIMs). Each solid line gives the estimated probability of Jackson Hole (JH) ancestry for an AIM. Green lines denote cases of credible directional introgression (95% CIs for α that exclude zero) and purple lines denote credible cases of restricted introgression (95% CIs for β > 0) (gray lines denote clines not credibly different from the genome average). The dashed line gives the null expectation based on genome-wide admixture. Boxplots show the distribution of cline parameters α (c) and β (d) across loci for each linkage group (based on n = 115 butterflies). Boxes denote the 1st and 3rd quartile with the median given by the midline; whiskers extend to the minum and maximum value or 1.5× the interquartile range with points for more extreme values. Source data are provided as a Source Data file.