Fig. 5: Expected and observed numbers of SNPs with exceptional patterns of introgression in the Dubois hybrid zone and extreme ancestry frequencies in Jackson Hole Lycaeides.

Panels a–f show results when considering the top 10% of AIMs in each category. Histograms give null expectations from randomization tests, and vertical solid lines show the observed number of AIMs exhibiting a given pattern. Comparisons shown are directional introgression of Jackson Hole alleles (high α) and high L. idas ancestry (in Jackson Hole) (a), directional introgression of L. melissa alleles (low α) and high L. melissa ancestry (b), directional introgression of Jackson Hole alleles (high α) and high L. melissa ancestry (c), directional introgression of L. melissa alleles (low α) and high L. idas ancestry (d), restricted introgression (high β) and high L. idas ancestry (e), and restricted introgression (high β) and high L. melissa ancestry (f). Panels g–i show how these results are affected by considering different levels of stringency (i.e., by examining the most extreme 10% to the top 1% of AIMs with each pattern), and when considering only the Z chromosome (g) or only the autosomes (h). Here, circles denote the ratio of the observed to expected overlap from the null, and the circles are filled (P ≤ 0.05) or not (P  > 0.05) to denote whether the overlap is greater than expected by chance from a one-sided randomization test. Source data are provided as a Source Data file.