Fig. 4

Plots showing patterns of genomic and geographic introgression across 32 A. caudacutus and A. nelsoni populations (n = 286). a Genomic clines calculated in introgress plotted as the observed frequency of A. caudacutus homozygote genotypes (1.0) against the hybrid index (calculated as the proportion of A. caudacutus alleles across all loci). Black lines show markers that deviate significantly from neutral introgression and gray lines show markers that do not deviate from neutral patterns of introgression. b Geographic clines calculated for 29 markers plotted as the frequency of caudacutus alleles across an 800 km sampling transect. Neutral markers are in gray, diagnostic markers in black, mitochondrial markers in red, z-linked markers in green, and an autosomal marker in blue. c Geographic clines calculated for five morphological traits. Weight is in black, wing chord in blue, bill length in gray, plumage amount in green, and plumage definition in red