Supergenes on Steroids

Abstract

At the birth of supergenes, the genomic landscape is dramatically re-organized leading to pronounced differences in phenotypes and increased intrasexual diversity. Two of the best-studied supergenes in vertebrates are arguably the inversion polymorphisms on chromosomes 2 and 11 in the white-throated sparrow (Zonotrichia albicollis) and the ruff (Calidris pugnax), respectively. In both species, regions of suppressed recombination determine plumage coloration and social behavioral phenotypes. Despite the apparent lack of gene overlap between these two supergenes, in both cases the alternative phenotypes seem to be driven largely by alterations in steroid hormone pathways. Here, we explore the interplay between genomic architecture and steroid-related genes. Due to the highly pleiotropic effects of such genes and their universal involvement in social behavior and genomic architecture, forces favouring their linkage are likely to have substantial effects on the evolution of behavioral phenotypes, individual fitness, and life history strategies. We propose that the differentiation of steroid-related genes, inside both supergenes, lies at the core of phenotypic differentiation in both of these interesting species.

Genetic basis of speciation and adaptation: from loci to causative mutations

“…For example, chromosomal inversions can capture adaptive linked mutations (e.g. Maney & Küpper [88] and Villoutreix et al . [69] in this issue).…”