Digest: Sex-specific benefits of mitochondrial introgression

Disrupting mitochondrial and nuclear coadaptation is expected to reduce fitness, especially in males and with age. But is that always true? Garlovsky et al. (2025) tested this in a panel of Drosophila lines, assessing reproductive success across sex and age. Unexpectedly, new mito-nuclear combinations had limited impact on reproduction and even conferred a fitness advantage to some males. These findings challenge current views, suggesting that mitochondrial replacement can sometimes enhance fitness.