sweeps at linked loci

Chevin L-M, Billiard S & Hospital F 2008 Hitchhiking both ways: effect of two interfering selective sweeps on linked neutral variation. Genetics 180:301-316.

• we also simulated the sampling of a small number of individuals (2n = 50 gametes) to assess the properties of the frequency spectrum
• calculated as in Kim (2006)

• there is an excess of variants at intermediate frequencies (from 15 to 35) relative to the standard neutral case
• this latter feature is commonly interpreted as the outcome of selective forces maintaining diversity, i.e., balancing selection
• excess of high-frequency derived variants, excess of intermediate-frequency variants, and lack of low-frequency variants relative to the neutral expectation − appear as a distinctive pattern of a double selective sweep

• we assumed here that selective sweeps had independent (multiplicative) effects on fitness
• epistasis between selected loci may also influence the neutral polymorphism pattern of interfering sweeps in a specific manner
• it could be possible to identify selective interactions a posteriori