Mating preferences can drive expansion or contraction of major histocompatibility complex gene family. Posted on 2020-03-132020-03-13 by Jacek Radwan In a series of commuter simulations described in a paper recently published in Proceedings of the Royal Society B, Jacek Radwan and Piotr Benkowski reveal unexpected potential of MHC-based mating preferences to drive evoltion of MHC gene number.