Rethinking mitochondrial heteroplasmy: selection, conflict and adaptation

Area of Science:

• Evolutionary biology
• Genetics
• Mitochondrial genomics

Background:

• Mitochondrial DNA (mtDNA) variation influences species evolution, but its role within individuals is less understood.
• Eukaryotic cells contain multiple mtDNA copies; sequence differences result in heteroplasmy, a significant source of intra-organismal genetic diversity.

Purpose of the Study:

• To explore the evolutionary significance of heteroplasmy in animals.
• To investigate selective pressures acting on mtDNA at the intra-individual level.
• To assess heteroplasmy as a reservoir of adaptive potential.

Main Methods:

• Review of natural selection shaping mtDNA dynamics at population and species levels.
• Exploration of intra-individual selection pressures on heteroplasmy.
• Analysis of theoretical models on paternal mtDNA transmission and heteroplasmy.

Main Results:

• Natural selection influences mtDNA dynamics through mito-nuclear coadaptation, environmental factors, sex-specific selection, and balancing selection.
• Heteroplasmy enables multi-level selection, potentially leading to synergistic or antagonistic evolutionary outcomes.
• Paternal mtDNA transmission may offer adaptive benefits by increasing intra-individual mtDNA diversity.

Conclusions:

• Heteroplasmy represents an underappreciated source of adaptive potential within organisms.
• Intra-individual mtDNA diversity can enhance evolutionary capacity, particularly under environmental stress.
• Understanding heteroplasmy is crucial for comprehending organismal adaptation in a changing world.