To the roots: reconstruction of the ancestral state of the dorid feeding apparatus

Diet-driven ecological radiation has been proposed as a key factor in the diversification of Nudibranchia. Members of Doridina, one of the two major clades of nudibranchs, have a remarkably wide range of dietary preferences. The morphology of the feeding apparatus is related to prey preferences and feeding mechanisms. Therefore, the investigation of the evolutionary changes in the morphology of the feeding apparatus can provide valuable insights into the evolution of Doridina. Recent significant changes in our understanding of the phylogeny of Doridina have highlighted the need to re-evaluate current hypotheses on the evolution of the buccal armature morphology and correlated dietary shifts in this group. To address this, we compiled and analysed a comprehensive dataset that combined phylogenetic and morphological data to reconstruct the evolution of the buccal armature in Doridina. We also review the feeding biology of various groups of dorids to provide a deeper view of the evolution of the morphology of the feeding apparatus. We hypothesised the plesiomorphic conditions of the buccal armature for each large clade of Doridina and for the entire group. Within Doridina, there is a strong phylogenetic correlation with prey preference as major changes in the diet preferences of several clades led to significant transformations in radular morphology. We also discovered several cases of retention of plesiomorphic radular morphology and feeding mechanisms in different phylogenetic lineages of Doridina.