Selfish genes and meiotic drive

Work by Gerald Wilkinson and colleagues3 on stalk-eyed flies (Diopsidae), described on page 276, provides the strongest evidence to date about the nature of some of the genes females prefer. As their name suggests, stalk-eyed flies have their eyes perched on the end of side-projecting stalks (see the cover of this issue). These can reach ridiculous proportions. In two of the species studied, males have considerably greater eye span than females, and male eye span even exceeds body length. In both of these species females show a strong preference for males with a large eye span. In a third species, male eye span was much shorter (indeed no different to female eye span) and there was no female choice.