Meiotic drive genes cause the degeneration of non-carrier sperm to bias transmission in their favour. Males carrying meiotic drive are expected to suffer reduced fertility due to the loss of sperm and associated harmful side-effects of the mechanisms causing segregation distortion. However, sexual selection should promote adaptive compensation to overcome these deleterious effects. We investigate this using SR, an X-linked meiotic drive system in the stalk-eyed fly, Teleopsis dalmanni. Despite sperm destruction caused by drive, we find no evidence that SR males transfer fewer sperm to the female’s spermathecae (long-term storage organs). Likewise, migration from the spermathecae to the ventral receptacle for fertilisation is similar for SR and wildtype male sperm, both over short and long time-frames. In addition, sperm number in storage is similar even after males have mated multiple times. Our study challenges conventional assumptions about the deleterious effects of drive on male fertility. This suggests that SR male ejaculate investment per ejaculate has been adjusted to match sperm delivery by wildtype males. We interpret these results in the light of recent theoretical models that predict how ejaculate strategies evolve when males vary in the resources allocated to reproduction or in sperm fertility. Adaptive compensation is likely in species where meiotic drive has persisted over many generations and predicts a higher stable frequency of drive maintained in wild populations. Future research must determine exactly how drive males compensate for failed spermatogenesis, and how such compensation may trade-off with investment in other fitness traits.

Sperm allocation with variation in female quality.To test for differences in sperm allocation by SR and ST males, we examined sperm storage by females after a single mating. Males were tested with large and small females to test whether sperm allocation varied with female quality. Allocation was assessed through counts of sperm stored in the spermathecae.Spermathecae.csvSperm movement to the site of fertilisation.We examined sperm that migrated to the ventral receptacle (VR), the site of egg fertilisation, when females were mated to an SR or ST male. Males were tested with large and small females, and the proportion of VR pouches that were filled (contained a sperm) or empty were counted.VR.csvSperm allocation across sequential matings (multiple mating).To examine SR and ST male sperm number across successive matings, sperm allocation was assessed through counts of sperm stored in spermathecae after a male’s first, second, and third mating. In this experiment, we did not vary female size, but selected mid-sized females with eyespan between 5.25mm – 5.95mm.MultipleMating.csvSperm allocation across sequential matings (third mating).To examine sperm number after successive matings, sperm allocation was assessed through counts of sperm stored in spermathecae on a male’s third mating. Females were mid-sized as before.ThirdMating.csv