Absence of Mother’s Curse for performance traits among divergent mtDNAs in heterozygous nuclear backgrounds in Drosophila

Mother's Curse (MC) posits that selection on mtDNA should be stronger in females than in males due to maternal inheritance of mtDNA. This predicts that phenotypic variation among mtDNA genotypes should be lower for females and higher for males. There is conflicting experimental evidence for MC. Most studies of MC have used a common, homozygous nuclear background and have not explored the influence of divergent mtDNAs as strong predictors of MC effects. We address both issues by assaying performance traits among mtDNAs of varying levels of divergence on heterozygous backgrounds. The data fail to support the MC hypothesis and even reveal the opposite effect that females have greater phenotypic variation across mtDNAs. MC may operate in some contexts, but it is not a consistent force in evolutionary genetics.