Abstracts (first author)
Inversions, supergenes and the genomic evolution of loci of large effect
Supergenes are defined as clusters of genetic elements maintaining fitness-related traits maintained in high linkage disequilibrium in response to selection for specific combinations of those traits. Recent studies have uncovered that supergenes may be maintained by structural variation presumed to help avoid recombination and the deleterious effects of maladaptive trait combinations. Chromosomal inversions are well-known for their suppressing effect on recombination, and can lock together multiple beneficial gene variants controlling specific trait combinations. There are historical examples, as well as numerous new cases of structural variation associated with the maintenance of well-differentiated morphotypes, ecotypes, or species in sympatry in diverse taxa. Chromosomal rearrangements are therefore important mechanisms of genomic architecture evolution, which merge the control of multiple beneficial traits under a simple inheritance. Thus they provide a way of building up loci of large phenotypic effect, often found to be associated with adaptive variation and radiations. But exactly how multiple beneficial traits become recruited within inversions at the population level is still unclear. In this talk, I will discuss the origins of rearrangement-associated adaptations from plant and animal taxa. I will highlight the role of the ecology of each individual trait and their different combinations, the role of the selection regimes underlying the fitness benefits of tight linkage, and the role of introgression. A continuum of genomic architectures underlies adaptive variation from stable polymorphisms within populations to ecotypes and to ecological speciation. Inversions and supergenes are therefore excellent genomic microcosms to improve our understanding of the process of adaptation and the ecology and tempo of the build-up of linkage disequilibrium between multiple traits.