Heteroplasmy and Individual Mitogene Pools: Characteristics and Potential Roles in Ecological Studies

SIMPLE SUMMARY: The mitochondrial genome is a multicopy circular DNA with high mutation rates due to replication and repair errors. Mitochondrial DNA (mtDNA) heteroplasmy refers to the presence of more than one type of mtDNA in an individual. A mitochondrion, cell, tissue, organ, or an individual body may hold multiple variants, both inherited and developed over a lifetime. We review the characteristics, dynamics, and functions of mtDNA heteroplasmy and propose the concept of an individual mitogene pool to discuss individual genetic diversity from multiple angles to guide how the individual mitogene pool with novel genetic markers can be applied to ecological research. ABSTRACT: The mitochondrial genome (mitogenome or mtDNA), the extrachromosomal genome, is a multicopy circular DNA with high mutation rates due to replication and repair errors. A mitochondrion, cell, tissue, organ, or an individual body may hold multiple variants, both inherited and developed over a lifetime, which make up individual mitogene pools. This phenomenon is also called mtDNA heteroplasmy. MtDNA variants influence cellular and tissular functions and are consequently subjected to selection. Although it has long been recognized that only inheritable germline heteroplasmies have evolutionary significance, non-inheritable somatic heteroplasmies have been overlooked since they directly affect individual fitness and thus indirectly affect the fate of heritable germline variants. This review focuses on the characteristics, dynamics, and functions of mtDNA heteroplasmy and proposes the concept of individual mitogene pools to discuss individual genetic diversity from multiple angles. We provide a unique perspective on the relationship between individual genetic diversity and heritable genetic diversity and guide how the individual mitogene pool with novel genetic markers can be applied to ecological research.