Do women live longer because of their mitochondria?

Duur K. Aanen, Johannes N. Spelbrink, and Madeleine Beekman Review article: What cost mitochondria? The maintenance of functional mitochondrial DNA within and across generations Phil. Trans. R. Soc. B. 2014 369 20130438; doi:10.1098/rstb.2013.0438 (published 26 May 2014) http://rstb.royalsocietypublishing.org/content/369/1646/20130438.abstract "Uniparental transmission, in combination with an mtDNA copy number bottleneck and germline selection, allows the selection of functional mtDNA molecules. But biology would not be so interesting if some of these organism-level adaptations did not set the stage for new problems. First, uniparental transmission implies the absence of recombination between genetically different mtDNA variants. The absence of recombination, in combination with the high mutation rate of mtDNA, leads to the accumulation of deleterious mutations in a ‘Muller's ratchet’ [49]. Germline selection against deleterious mtDNA mutations will counteract or at least slow down this process. Second, if cytoplasmic elements are transmitted by only one sex, all that matters for their evolution is their effect on the fitness of that sex. Thus, if transmission occurs only via females, mutations harmful to males will not be selected against, if they are neutral to females, or even be selected for if they are beneficial to females (‘Mother's Curse’; [50,51]). Empirical evidence for ‘Mother's Curse’ comes from fruit flies in which mtDNA mutations have a disproportional effect on gene expression of males compared with females [52] leading to faster ageing of male flies [53]. In humans, a relatively common mitochondrial haplotype is associated with reduced sperm motility (asthenozoospermia) [54]. As females do not produce sperm, there is no equivalent trait in females for selection to act on. Similar detrimental consequences of uniparental inheritance are found in flowering plants, including many agricultural crops (reviewed in [55]) and fungi [56]. Often, mutations that are only detrimental to one sex are hidden, as natural selection will favour compensatory mutations in the nuclear genome [51,57–59]."