Data from: Sex differences in lifespan: females homozygous for the X chromosome do not suffer the shorter lifespan predicted by the unguarded X hypothesis
Brengdahl, Martin, Linköping University
Kimber, Christopher M., Linköping University
Maguire-Baxter, Jack, Linköping University
Friberg, Urban, Linköping University
Published Jan 09, 2018 on Dryad.
Cite this dataset
Brengdahl, Martin; Kimber, Christopher M.; Maguire-Baxter, Jack; Friberg, Urban (2018). Data from: Sex differences in lifespan: females homozygous for the X chromosome do not suffer the shorter lifespan predicted by the unguarded X hypothesis [Dataset]. Dryad. https://doi.org/10.5061/dryad.8pb6r
Lifespan differs between the sexes in many species. Three hypotheses to explain this interesting pattern have been proposed, involving different drivers: sexual selection, asymmetrical inheritance of cytoplasmic genomes, and hemizygosity of the X(Z) chromosome (the unguarded X hypothesis). Of these, the unguarded X has received the least experimental attention. This hypothesis suggests that the heterogametic sex suffers a shortened lifespan because recessive deleterious alleles on its single X(Z) chromosome are expressed unconditionally. In Drosophila melanogaster, the X chromosome is unusually large (~20% of the genome), providing a powerful model for evaluating theories involving the X. Here, we test the unguarded X hypothesis by forcing D. melanogaster females from a laboratory population to express recessive X-linked alleles to the same degree as males, using females exclusively made homozygous for the X chromosome. We find no evidence for reduced lifespan or egg-to-adult viability due to X homozygozity. In contrast, males and females homozygous for an autosome both suffer similar, significant reductions in those traits. The logic of the unguarded X hypothesis is indisputable, but our results suggest that the degree to which recessive deleterious X-linked alleles depress performance in the heterogametic sex appears too small to explain general sex differences in lifespan.
Lifespan data from D. melanogaster (the Dahomey laboratory-adapted population), measured in vials. Note that Line and Vial numbers must be interpreted as specific to the Chromosome with which they occur. Numerical columns are days since start of experiment and their content is number of deaths since previous column.
Egg-to-adult viability data from D. melanogaster (the Dahomey laboratory-adapted population), measured in vials. Note that Line numbers must be interpreted as specific to the Chromosome with which they occur. Focal F is number of eclosed females and Focal M number of eclosed males. Ebony is number of eclosed competitor flies.