A number of species are affected by sex ratio meiotic drive (SR), a selfish genetic element located on the X chromosome that causes dysfunction of Y-bearing sperm. SR is transmitted to up to 100% of offspring, causing extreme sex ratio bias. SR in several species is found in a stable polymorphism at a moderate frequency, suggesting there must be strong frequency-dependent selection resisting its spread. We investigate the effect of SR on female and male egg-to-adult viability in the Malaysian stalk-eyed fly, Teleopsis dalmanni. SR meiotic drive in this species is old, and appears to be broadly stable at a moderate (~20%) frequency. We use large-scale controlled crosses to estimate the strength of selection acting against SR in female and male carriers. We find that SR reduces the egg-to-adult viability of both sexes. In females, homozygous females experience greater reduction in viability (sf = 0.242) and the deleterious effects of SR are additive (h = 0.511). The male deficit in viability (sm = 0.214) is not different from that in homozygous females. The evidence does not support the expectation that deleterious side-effects of SR are recessive or sex-limited. We discuss how these reductions in egg-to-adult survival, as well as other forms of selection acting on SR, may maintain the SR polymorphism in this species.
Egg-to-adult_viability_raw_data
This is the raw egg-to-adult viability data. The first column is a unique fly ID. The second column is the sex of the fly, with F for female and M for male. The third column denotes food condition, with H for High, M for Medium and L for Low. The fourth column denotes the genotype assigned to that fly. Here, the meiotic drive chromosome is denoted SR and the standard chromosome is denoted X. Flies that were not genotyped are recorded as NG. Genotyping failure is denoted by NA. The fifth column denotes the date that eggs were collected. The final column, Cage, is a number identifying replicate cages within each Collection_Date/Food_Condition combination.
Egg-to-adult_viability_processed_data
Each row of this data file is a replicate egg-to-adult viability estimate at the level of the cage. The first set of analyses of the manuscript were carried out on this dataset. This data was obtained by processing the Egg-to-adult_raw_viability_data file. This processing involved the generation of a unique cage identifier, made up from a combination of Collection_Date, Food_Condition, and Cage from the raw data file. Flies from the raw data were grouped by this identifier and total number of male and female flies, as well as the number of genotyped male and female flies, were counted. A replicate egg-to-adult viability estimate was then made at the level of the cage for each genotype, as described in the manuscript methods. Data were then split so that each row gives a replicate estimate for just one genotype. The first column in this dataset, Cage_ID, is the unique cage identifier. The second column, Food_Condition, denotes food condition, with H for High, M for Medium, and L for Low. The third column, Collection_Date refers to the date eggs were collected. The fourth column, Tot_No, is the total number of flies that eclosed from a given cage (out of a total of 72). The fifth and sixth columns, F_No, and M_No refer to the total number of female and male flies that eclosed from a given cage respectively. The seventh and eighth columns, Males_Genod and Females_Genod, refer to the total number of males and females that were genotyped for a given cage. The ninth column, Geno_No, is the sum of the previous two columns. The tenth column, Genotype, is the genotype being referred to on each row. Here, SR describes the meiotic drive chromosome and X describes the standard chromosome. The final column, W, is the cage-level egg-to-adult viability estimate for that genotype.