Concordantly, many studies on male-specific mitonuclear effects find irregular epistasis rather than increased mitochondrial performance in coadapted mitonuclear combinations (Dobler et al., 2014).In females, selection on mitonuclear genotype would be more efficient in terms of generating mitonuclear coadaptation, simply because nuclear genes and mt DNA cosegregate in females (Rand et al., 2004; Wade, 2014).The larvae develop for 3 weeks, and copulate soon after emergence from beans as adults. This species is facultatively aphagous and can complete its reproductive cycle with the resources acquired during the larval stage (Fox, 1993).However, adult feeding increases both longevity and productivity of the beetles (Fox, 1993).Mitochondrial function relies on the coordinated expression of over a thousand nuclear genes and a few dozen mitochondrial genes (Calvo and Mootha, 2010).This suggests that ageing phenotypes may commonly be subject to a complex set of epistatic interactions between the nuclear and the mitochondrial genomes.
However, it has been estimated that the rate of nuclear compensatory evolution is less than one-fourth that of male-harming mitochondrial mutations (Wade, 2014), making mitonuclear coevolution less efficient in males.
An important but overlooked aspect in the study of sex-specific reproductive senescence derives from the fact that reproductive traits in one sex, affected by mitochondrial genetic variation (Dowling et al., 2007b; Yee et al., 2013), may have important effects on reproductive phenotypes in the other sex.
Reproduction is an outcome of molecular interactions between the sexes and research over the past few decades has clearly demonstrated that male traits influence female reproductive performance (Arnqvist and Rowe, 2005).
Maternal inheritance of mitochondria predicts sex differences in the efficacy of selection on mitonuclear genotypes that should result in differences between females and males in mitochondrial genetic effects.
Mitonuclear genotype of a focal individual may also indirectly affect trait expression in the mating partner.