The genomics of an adaptive radiation: insights across the Heliconius speciation continuum

Fueled by new technologies that allow rapid and inexpensive assessment of fine scale individual genomic variation, researchers are making transformational discoveries at the interface between genomes and biological complexity. Here we review genomic research in Heliconius butterflies - a radiation characterized by extraordinary phenotypic diversity in warningly colored wing patterns and composed of a continuum of taxa across the stages of speciation. These characteristics, coupled with a 50-year legacy of ecological and behavioral research, offer exceptional prospects for genomic studies into the nature of adaptive differences and the formation of new species. Research in Heliconius provides clear connections between genotype, phenotype, and fitness of wing color patterns shown to underlie adaptation and speciation. This research is challenging our perceptions about how speciation occurs in the presence of gene flow and the role of hybridization in generating adaptive novelty. With the release of the first Heliconius genome assembly, emerging genomic studies are painting a dynamic picture of the evolving species boundary. As the field of speciation genomics moves beyond describing patterns, towards a more integrated understanding of the process of speciation, groups such as Heliconius, where there is a clear speciation continuum and the traits underlying adaptation and speciation are known, will provide a roadmap for identifying variation crucial in the origins of biodiversity.