Résumé
We probe the history of rapidly radiating Heliconius butterflies by means
of 20 new genome assemblies and employ them to investigate the genomic
architecture of gene flow among lineages. By developing a test to
distinguish incomplete lineage sorting from introgression, we demonstrate
that histories of loci that differ from the species tree arose mostly
through introgression. Moreover, these loci are underrepresented in low
recombination and gene-rich regions, consistent with the purging of
introgressed alleles tightly linked with incompatibility loci.
Additionally, our analysis identifies an inversion that captures a color
pattern switch locus which was transferred between lineages via
introgression and is convergent with a similar rearrangement in another
part of the genus. This analysis of multiple de novo genome sequences
enables an improved understanding of the importance of introgression and
selective processes in adaptive radiation.