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. 

Ants are powerful models for studying genome evolution, mitonuclear coevolution, and their role in sociality. Their eusocial structure, with distinct castes and extreme lifespan differences between queens and workers—despite sharing the same genome—provides a unique system to explore the genetic basis of social behavior and longevity. As queens transmit mitochondria to entire colonies, ants offer a natural framework for investigating mitonuclear interactions and their role in metabolism, aging, and reproductive division of labor. This becomes even more intriguing when considering their haplodiploid reproductive system: females are diploid, while males are haploid, leading to extremely strong selection on the coevolution between nuclear and mitochondrial genomes within the same cell. These features make ants an exceptional system for understanding the evolutionary forces shaping genomes and complex traits.

Work in Progress

Stick insects (Phasmatodea) are a fascinating model for studying evolutionary dynamics due to their remarkable diversity and unique traits. This group has been central to the debate on trait reversibility, particularly concerning the evolution of wings. Phasmids exhibit a complex evolutionary history, with multiple instances of wing loss and subsequent regains, defying Dollo’s law, which posits the irreversibility of complex trait loss. Their diversity of reproductive strategies, including both bisexual and parthenogenetic species, offers a natural laboratory for investigating how molecular architectures underlying lost traits can persist and remain functional through pleiotropic effects and co-expression network constraints. Moreover, stick insects are ideal for studying the evolutionary forces driving trait persistence, reversal, and diversification, providing insights into broader evolutionary principles such as adaptation, pleiotropy, and network connectivity. Their capacity to challenge long-standing evolutionary paradigms makes stick insects a powerful system for exploring the dynamic interplay between genotype, phenotype, and ecology.

In the last few years, birds have emerged as intriguing study subjects for longevity analyses. This class of vertebrates shows an extraordinary range of lifespans: from three years for the red-faced warbler (Cardelilina rubrifrons—Passeriformes) to 84 years for the American flamingo (Phoenicopterus ruber—Phoenicopteriformes). Interestingly, they show specific physiological features that are expected to accelerate aging (including particularly high  metabolic rates and body , and lower insulin sensitivity) but they generally live two to three times longer than similarly-sized mammals. This characteristic make them an exciting case study to investigate the mechanisms of lifespan variations and aging.