The genomic mechanisms that are associated with the processes of diversification of lineages and adaptive radiations are nowadays studied in a wide range of organisms. The availability of large-scale genomic resources has shown that a wide array of genome-wide changes could predispose particular lineages to diversify adaptively. Besides these overall genomic features being potentially linked with the rapid diversification, there is a clear and essential role played by ancient polymorphism and hybridization events in shaping adaptive radiation.
Anemonefishes are an interesting group to extend our understanding of the role played by hybridization in the processes of diversification and adaptation. These iconic coral reef fishes, which have an obligate mutualism with sea anemones, consist of 28 recognized species and two natural hybrids. Previous work suggested that the rapid diversification of anemonefishes was linked to hybridization events among members of the radiation. This was illustrated by recurrent cytonuclear inconsistency observed in the group, and these patterns were associated with a substantial increase in diversification rate. Hybridization is also still happening in the group, as shown by the presence of two natural hybrids, Amphiprion leucokranos and A. thiellei.
Here, we present some recent works investigating the occurrence of ancient hybridization events during the evolution of anemonefishes. The results are based on whole-genome sequencing of all anemonefish species and indicate an important role of this process in the evolution of the group. We discuss the phylogenetic patterns of these events and describe the impact that hybridization had on the genomic architecture of the anemonefishes.