Ancestral gene flow at the base of Heliconius
(A) Posterior probabilities of species trees for major Heliconius clades inferred from BPP analysis of 200-locus blocks (each spanning 1–3 Mb) across the genome under the multispecies coalescent (MSC) model with no gene flow. The y-axis shows the posterior probability of species trees and ranges from 0 to 1. Colors correspond to the nine most common MAP trees, summarized by lumping species in the melpomene-silvaniform clade (Bes, Num, Mel) into a single tip (BNM); see Figure S1 for full trees. Proportions of coding and noncoding blocks with each tree as a MAP tree are shown in parentheses. (B, C) Two scenarios of early divergence of Heliconius: (B) erato-early versus (C) aoede-early. Each tree is a MAP tree from a block having the MAP tree supporting each scenario, with estimates of branch lengths (posterior means). (D, E) Introgression histories estimated under an MSC model with introgression (MSci) corresponding to the two scenarios based on coding loci in chromosome 1 (3,517 coding loci; see Figures S7–S8). (F) Proportions of trees of scenarios 1 or 2 in each chromosome in order of increasing number of loci (used as a proxy for chromosome size). Chromosome 21 is placed at the right end. Number of blocks is shown on top of each bar. Tal: Eueides tales, Mel: H. melpomene, Bes: H. besckei, Num: H. numata, Bur: H. burneyi, Dor: H. doris, Aoe: H. aoede, Era: H. erato, Sar: H. sara.