Male eyespan size is associated with meiotic drive in wild stalk-eyed flies ( Teleopsis dalmanni )

This study provides the first direct evidence from wild populations of stalk-eyed flies to support the hypothesis that male eyespan is a signal of meiotic drive. Several stalk-eyed flyspecies are known to exhibit X-linked meiotic drive. A recent quantitative trait locusanalysis in Teleopsis dalmanni found a potential link between variation in male eyespan, a sexually selectedornamental trait, and the presence of meiotic drive. This was based on laboratory populations subject to artificial selection for male eyespan. In this study, we examined the association between microsatellite markers and levels of sex ratiobias ( meiotic drive) in 12 wild T. dalmanni populations. We collected two data sets: (a) brood sex ratiosof wild-caught males mated to standard laboratory females and (b) variation in a range of phenotypic traitsassociated with reproductive success of wild-caught males and females. In each case, we typed individuals for eight X-linked microsatellite markers, including several that previously were shown to be associated with male eyespan and meiotic drive. We found that one microsatellite marker was very strongly associated with meiotic drive, whereas a second showed a weaker association. We also found that, using both independent data sets, meiotic drivewas strongly associated with male eyespan, with smaller eyespan males being associated with more female-biased broods. These results suggest that mate preferencefor exaggerated male eyespan allows females to avoid mating with males carrying the meiotic drivegene and is thus a potential mechanism for the maintenance and evolution of female mate preference.