The gene family that cheats Mendel

Abstract

Some alleles of the wtf gene family can increase their chances of spreading by using poisons to kill other alleles, and antidotes to save themselves.

Keywords: S. pombe; chromosomes; evolution; evolutionary biology; genes; genetic conflict; genomics; infertility; meiotic drive; segregation distortion; spore killer.

Figure 1.. The poison-antidote and killer-target models of selfish drivers.

In both models, a particular allele has an increased chance of being passed on to the next generation because it produces a toxin to kill gametes that do not carry it. (A, B) In the poison-antidote model, cells produce a toxin (shown as skull-and-crossbones) that can be neutralized by an antidote (shown as a pill); the alleles that do not code for either are shown in gray. In the single-gene model (A) the same gene codes for both the poison and the antidote through alternative transcription. Nuckolls et al. show that the gene wtf4 is a selfish driver in Schizosaccharomyces yeasts. Hu et al. show that two other genes in the wtf family (cw9 and cw27) are also selfish drivers. In the two-gene model (B) different genes produce the poison and antidote, as in the fungus Neurospora (Hammond et al., 2012). (C) In the killer-target model, the toxin only destroys cells that contain alleles with a specific target marker (shown here by concentric black circles). This is the case in Drosophila, where the segregation distortion (Sd) allele acts by killing gametes that contain a sensitive Responder (Rsp^s) marker (Larracuente and Presgraves, 2012).