Data from: Butterfly genome reveals promiscuous exchange of mimicry adaptations among species

The evolutionary importance of hybridization and introgression has long
been debated. Hybrids are usually rare and unfit, but even infrequent
hybridization can aid adaptation by transferring beneficial traits between
species. Here we use genomic tools to investigate introgression in
Heliconius, a rapidly radiating genus of neotropical butterflies widely
used in studies of ecology, behaviour, mimicry and speciation. We
sequenced the genome of Heliconius melpomene and compared it with other
taxa to investigate chromosomal evolution in Lepidoptera and gene flow
among multiple Heliconius species and races. Among 12,669 predicted genes,
biologically important expansions of families of chemosensory and Hox
genes are particularly noteworthy. Chromosomal organization has remained
broadly conserved since the Cretaceous period, when butterflies split from
the Bombyx (silkmoth) lineage. Using genomic resequencing, we show hybrid
exchange of genes between three co-mimics, Heliconius melpomene,
Heliconius timareta and Heliconius elevatus, especially at two genomic
regions that control mimicry pattern. We infer that closely related
Heliconius species exchange protective colour-pattern genes promiscuously,
implying that hybridization has an important role in adaptive radiation.