The class Bivalvia is a highly successful and ancient taxon including 25,000 living species. During their long evolutionary history bivalves adapted to a wide range of physicochemical conditions, habitats, biological interactions, and feeding habits. Bivalves can have strikingly different size, and despite their apparently simple body plan, they evolved very different shell shapes, and complex anatomic structures. 

One of the most striking features of this class of animals is their peculiar mitochondrial biology: some bivalves have facultatively anaerobic mitochondria that allow them to survive prolonged periods of anoxia/hypoxia. Moreover, 100+ species have now been reported showing the only known evolutionarily stable exception to the strictly maternal inheritance of mitochondria in animals, named doubly uniparental inheritance. Mitochondrial activity is fundamental to eukaryotic life, and thanks to their diversity and unique features (two highly divergent mtDNA lineages, characterized by different dynamics, selective pressure, and segregation pattern), bivalves represent a great model system to study mitochondrial biology, particularly mitochondial inheritance and mitonuclear coevolution.

Bivalves also shows the highest lifespan disparity within Metazoa, ranging from 1 to 500+ years and includes the longest-lived non-colonial animal species known so far, the clam Arctica islandica. Bivalves therefore represent important resources to provide insights into the evolution of extended longevity. 

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Work in Progress

Work in Progress