Abstract

Gene duplications can facilitate adaptation and may lead to inter-population divergence, causing reproductive isolation. We used whole-genome re-sequencing data from 34 butterflies to detect duplications in two Heliconius species, H. cydno and H. melpomene. Taking advantage of three distinctive signals of duplication in short-read sequencing data, we identified 744 duplicated loci in H. cydno and H. melpomene. Duplications overlap genes significantly less than random in H. melpomene, consistent with the action of background selection against duplicates in functional regions of the genome. Duplicate loci that are highly differentiated between H. melpomene and H. cydno are widely distributed across the genome. Nine duplications may be under selection, including two duplications in close proximity with known wing colour pattern loci that differ between the two species, several gustatory receptors and an odorant binding protein. These candidates merit further investigation for a potential role in host plant and mate recognition differences between the species.