Abstract

Andrew Gillis

Oviparous chondrichthyans as emerging models of vertebrate development

As the sister group to bony fishes (including tetrapods), chondrichthyans represent a crucial phylogenetic data point for studies addressing the origin and diversification of jawed vertebrates. Oviparous (e.g. egg-laying) chondrichthyans are particularly useful for such studies, as their mode of development makes them amenable to both observation and experimental manipulation. I will present three examples of how experimental embryological studies using oviparous chondrichthyans have shed light on the evolution of important anatomical features of jawed vertebrates. These include: 1) The development of chondrichthyan branchial appendages, and their relationship to paired fins/limbs; 2) Dorsal-ventral pharyngeal endoskeletal patterning, and the serial homology of jaws and gill arches; and 3) The embryonic origin of chondrichthyan electroreceptive ampullary organs and mechanosensory neuromasts. These studies highlight oviparous chondrichthyans as emerging models of vertebrate development, and illustrate how developmental studies in phylogenetically informative taxa can shed light on the origin of anatomical novelty.