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.