The evolution of lifespan and ageing in African killifishes and beyond

Dario Riccardo Valenzano

Max Planck Institute for Biology of Ageing, Germany

African killifishes have colonised diverse environments, from rainforests to arid savannahs. Uniquely among vertebrates, to withstand seasonal habitat desiccation, they repeatedly evolved an annual life cycle. We sequenced the genomes of 45 African killifish species, including four de novo genome assemblies and annotations. We found that independent adaptations to annual environments are associated with large-scale genomic changes, including genome expansion and pervasive accumulation of deleterious amino acid substitutions in otherwise conserved genes. Population genetics in two annual species revealed that – also within species – evolution in dry environments is characterised by genome expansion and genomic hallmarks of weak selection. Overall, relaxed purifying selection prominently shapes genomes in annual environments both at macro- and microevolutionary scale, and is a prime candidate force moulding the evolution of a broad range of ageing phenotypes in annual killifishes.