The Interplay of Supergenes and Selfish Genetic Elements

Supergenes are clusters of linked loci that control alternative phenotypes involving multiple traits. While an increasing number of supergenes persisting as balanced polymorphisms within populations are being discovered, researchers have more to learn about the forces governing their evolution and long-term maintenance. Historically, supergenes were described as coadapted gene complexes that evolved because suppressed recombination locked beneficial allele combinations together while preventing maladaptive ones. A well-known byproduct of suppressed recombination is the accumulation of deleterious mutations. A less widely recognized consequence of suppressed recombination is that it can protect selfish genetic elements, including various types of transmission ratio distorters. In this review, we synthesize conceptual and empirical evidence connecting supergenes and selfish genetic elements. We show that selfish genetic elements frequently occur in supergenes, potentially promoting their spread but also destabilizing the genetic polymorphism. We conclude that intragenomic conflict plays a major role in the dynamics of supergenes.