Supergene evolution triggered by the introgression of a chromosomal inversion


Jay, P., Whibley, A., Frézal, L., de Cara, M. Á. R., Nowell, R. W., Mallet, J., Dasmahapatra, K. D., et al. (2018). Supergene evolution triggered by the introgression of a chromosomal inversion. Current Biology , 28, 1839-1845.


Supergenes are groups of tightly linked loci whose
variation is inherited as a single Mendelian locus
and are a common genetic architecture for complex
traits under balancing selection [1–8]. Supergene alleles
are long-range haplotypes with numerous mutations
underlying distinct adaptive strategies, often
maintained in linkage disequilibrium through the suppression
of recombination by chromosomal rearrangements
[1, 5, 7–9]. However, the mechanism governing
the formation of supergenes is not well
understood and poses the paradox of establishing
divergent functional haplotypes in the face of recombination.
Here, we show that the formation of the supergene
alleles encoding mimicry polymorphism in
the butterfly Heliconius numata is associated with
the introgression of a divergent, inverted chromosomal
segment. Haplotype divergence and linkage
disequilibrium indicate that supergene alleles, each
allowing precisewing-pattern resemblance to distinct
butterfly models, originate fromover a million years of
independent chromosomal evolution in separate lineages.
These ‘‘superalleles’’ have evolved from a chromosomal
inversion captured by introgression and
maintained in balanced polymorphism, triggering supergene
inheritance. This mode of evolution involving
the introgression of a chromosomal rearrangement is
likely to be a common feature of complex structural
polymorphisms associated with the coexistence of
distinct adaptive syndromes. This shows that the
reticulation of genealogies may have a powerful
influence on the evolution of genetic architectures in

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Last updated on 07/25/2019