Extended Data Fig. 5: Genetic evidence for current reproductive isolation between H. elevatus and H. melpomene.

a, Neighbour-joining tree based on autosomal sites sampled every 1 kb (166,989 sites). Values next to branches denote bootstrap values (based on 100 bootstrap iterations). Images of butterfly wings are copyright of the authors and Michel Cast. b, Distribution of species-diagnostic SNPs along chromosomes in wild-caught H. elevatus and H. melpomene. Species-diagnostic SNPs were defined as SNPs with an allelic difference of at least 0.8 between all Amazonian populations of H. elevatus and all H. melpomene populations. The physical location of SNPs along chromosomes (in Mb) are shown on top. For visualization purposes, SNP blocks were subsampled to show only 1 in every 20 SNPs. The lack of long tracts of heterozygous genotypes (or introgressed homozygous genotypes) suggests that there is no recent hybridization, followed by backcrossing, between these two species.