Data for: The suppression of a selfish genetic element increases a male's mating success in a fly

X chromosome meiotic drive (XCMD) kills Y-bearing sperm during
spermatogenesis, leading to the biased transmission of the selfish X
chromosome. Despite this strong transmission, some natural XCMD systems
remain at low and stable frequencies, rather than rapidly spreading
through populations. The reason may be that male carriers can have reduced
fitness, as they lose half of their sperm, only produce daughters, and may
carry deleterious alleles associated with XCMD. Thus, females may benefit
from avoiding mating with male carriers, yielding a further reduction in
fitness. Genetic suppressors of XCMD, which block the killing of Y sperm
and restore fair Mendelian inheritance, are also common and could prevent
the spread of XCMD. However, whether suppressed males are as fit as a
wild-type male remains an open question, and the effect that genetic
suppressors may have on a male’s mating success is rarely considered.
Here, we investigate the mating ability of XCMD males and suppressed XCMD
males in comparison to wild-type males in the fruit fly Drosophila
subobscura, where drive remains at a stable frequency of 20% in wild
populations where it occurs. We use both competitive and non-competitive
mating trials to evaluate male mating success in this system. We found no
evidence that unsuppressed XCMD males were discriminated against.
Remarkably, however, their suppressed XCMD counterparts had a higher male
mating success compared to wild-type controls. Unsuppressed XCMD males
suffered 12% lower offspring production in comparison to wild-type males.
This cost appears too weak to counter the transmission advantage of XCMD,
and thus the factors preventing the spread of XCMD remain unclear.