'Supergene' underlies genetic differences, sexual behavior in male ruff

Description

Ruffs seem to always have a nice surprise. Theunis and I are co-authors of a publication revealing that a ‘supergene’ determines the three male types in ruffs. This ‘supergene’ means that a relatively simple genetic system – a 4.5 megabase inversion linking many genes that code for manliness – underlies the evolution of the complex male phenotypes of ruffs.

If you do not know ruffs: ornamented dominant males hold territories on leks, collaborating with white subdominants, the satellites (5-20% of the males). The third type look like females; these cross-dressers are very rare (1%) and are called faeders. The discovery of faeders in 2006, by the Dutch farmer Joop Jukema and Theunis, was a surprise for many ruff experts, among them the UK and Canadian team leading this paper. Since 2006 this team has worked hard on unravelling the underlying genetics.

“Dutch” faeders were introduced in David Lank’s ruff aviary, at Simon Fraser University, and fathered quite some offspring. DNA (SNP) sequencing of this pedigreed population by first author Clemens Küpper led to finding the inversion on chromosome 11. Genomic screening of wild-type faeders and satellites from the Netherlands, Belarus and Russia, detected the flipped section on chromosome 11 in all satellites and faeders. Dominant males have the ancestral unflipped version and now the two versions cannot recombine, creating the ‘supergene’. A nice surprise! And great material for further work. Maybe this will help us understand how the odd frequencies of the three male types are maintained.