Meiotic drive in the sex chromosome system of the varying lemming, dicrostonyx torquatus pall. (Rodentia, microtinae)

Abstract

In the varying lemming, numerous fertile XY females occur regularly due to the X-linked mutation (X*). Their frequency both in natural populations and laboratory colonies turned out to be about twice higher than that expected under random segregation of heterochromosomes in both sexes. It has been shown in experiments that an excess of XY females resulted from a preferential segregation of the Y chromosome in males. Segregation distortion is not produced by selective embryonal mortality. Meiotic drive of the Y chromosome also causes a significant decrease of sex ratio. Although in the varying lemming meiotic drive is rather weak (the segregation ratio of the Y being 0·54-0·59), it seems to contribute essentially to the evolutionary spread and the maintenance of the X* mutation in populations. The example of Dicrostonyx and probably of other microtines also demonstrates the possible role of meiotic drive in the regulation of the population sex ratio in mammals. © The Genetical Society of Great Britain.