Meeting Abstract
In metazoans, mitochondria follow a strict mode of maternal inheritance. In theory, maternal inheritance will render selection ineffective in removing mitochondrial DNA mutations that are explicitly male-harming. Similarly, in species with XY sex determination, the X chromosome spends two-thirds of its evolutionary existence inside of females (since females are XX and males XY), which theory suggests could also lead to the accumulation of sexually-antagonistic fitness variation. Furthermore, this female-bias in the inheritance of the X chromosome increases the rate of co-transmission between allelic combinations on the X chromosome and mitochondrial genome to 67% (versus 50% for autosomal-mitochondrial allelic combinations), which should facilitate female-specific co-adaptation between mitochondrial and nuclear genomes, but potentially at the expense of male performance. Here, we test this hypothesis. We first created genetic strains of the fruit fly, Drosophila melanogaster, which possess one of five mtDNA haplotypes and five X chromosome genotypes, in all possible combinations, in an otherwise standardized autosomal background. We used these strains to explore whether genetic combinations of mtDNA haplotype and X chromosome exert sex-specific, potentially sexually-antagonistic effects on longevity. Our work helps elucidate the contribution of sexual asymmetry in the inheritance of particular genomic regions to the evolution of sex differences in life-histories.
