Genome rearrangements and adaptation: Can you have your cake and recombine it too?

Species that live across a range of different environments often exhibit local adaptation, in which particular genetic variants (alleles) are common in some locations and rare in others. If there is gene-flow between environments, and multiple genetic loci are involved in local adaptation, this may favour genome rearrangements that maintain favourable combinations of alleles at multiple loci that are all adapted to the same environment, by suppressing recombination. However, these rearrangements may also have costs, as they could preventing the formation of new combinations of alleles that may be better suited to new environmental conditions. We still know little about the specific mechanisms that suppress recombination to support local adaptation, and the extent to which these may limit future adaptation. I will present some recent findings on the structure and evolution of a local adaptation "supergene” in the African monarch butterfly that shed light on these topics. We have found that this region of the genome evolved in multiple steps through complex structural rearrangements. Nevertheless, recombination is not entirely suppressed, and this may allow the formation of new combinations of alleles that might sometimes be better adapted than the ancient ones. I will conclude with some evidence of such a potentially adaptive "recombinant”. Overall, our findings show that genome rearrangements may be far more dynamic in their evolution than previously thought.

[Host: BIODIV PhD Students]


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