The genetics-morphology-behaviour trifecta: unravelling the single greatest limitation affecting our understanding of chondrichthyan evolution

Sharks, rays and chimaera form the clade Chondrichthyes, an ancient group of morphologically and ecologically diverse vertebrates that has played an important role in our understanding of gnathostome evolution. Increasingly studies have are seeking to investigate evolutionary processes operating within the chondrichthyan crown group, with the broad aim of understanding the driving forces behind the vast phenotypic diversity observed amongst its constituent taxa. Genetic, morphological and behavioural studies have all contributed to our understanding of phenotypic evolution yet are typically considered in isolation in the context of Chondrichthyes. I argue that integrating these core fields of organismal biology is vital if we are to understand the evolutionary processes operating in contemporary chondrichthyan taxa, and how such processes have contributed to past phenotypic evolution. In light of the global extinction crisis facing this clade, this understanding is crucial if we are to successfully conserve rapidly declining chondrichthyan populations.