Abstract Mitochondrial DNA (mtDNA) variation is increasingly recognized for its role in shaping evolutionary changes at the species and population levels. Yet, its evolutionary relevance within individuals remains less explored. Eukaryotic cells typically carry multiple copies of mtDNA. When these copies differ in sequence, heteroplasmy arises—a form of intra-organismal genetic diversity with potentially profound biological implications. To elucidate the evolutionary significance of heteroplasmy