A resourceful genome: updating the functional repertoire and evolutionary role of animal mitochondrial DNAs

Highlights • Animal mitochondria are involved in many biological processes besides the production of ATP. • Some animals show non-standard mitochondrial features: unusual protein-coding gene content and/or mtDNA-encoded proteins with extramitochondrial localization and non-oxidative phosphorylation function. • These unusual mitochondrial features are good candidate factors affecting mitochondrial transmission or other aspects of mitochondrial biology, and they may have an important role in lineage-specific adaptations and speciation processes.