Supergenes in the news
New Heliconius supergene paper published in Nature by Joron and colleagues. We were delighted to see that supergenes, most famously found in the land snail Cepaea nemoralis, are fashionable again!
Supergenes are tightly linked groups of genes that in effect function as a single unit. Polymorphic supergenes, in which specific combinations of traits are maintained within a single population, have been described for ‘pin’ and ‘thrum’ Primula flowers as well as in insect mimicry and snail shell colour and banding. An outstanding question is how genes of diverse origin are brought together by natural selection. In a recent paper, Joron and colleagues have shown that in Heliconius butterflies it is chromosomal rearrangements that tighten the genetic linkage between at least two colour-pattern loci, thus forming a simple switch between complex adaptive phenotypes found in sympatry. Cool!