Emerging Patterns in the Functional and Developmental Genetics of Mimicry Supergenes

Development depends on the coordinated activity of many genes acting across time and space within each individual, yet many species can produce multiple discrete phenotypes. Such complex balanced polymorphisms are often controlled by supergenes, which are genomic regions containing tightly linked genetic elements that function together to direct alternative developmental programs. Supergene-controlled polymorphisms provide powerful models for understanding evolution and development, revealing how stable alternative fates emerge through the modulation of gene regulatory networks (GRNs). Here, we synthesize recent advances in the evolution, function, and developmental genetics of butterfly mimicry supergenes. We use these historically important systems to review how and why supergenes evolve. We then discuss how supergenes control the development of alternate wing patterns through GRN modification. Finally, we draw parallels with supergene polymorphisms in other organisms to frame general principles governing the evolution and developmental basis of balanced polymorphisms.