Sharks and rays represent one of the oldest offshoots in the evolutionary tree that gave rise to jawed vertebrate animals. This ancient lineage is represented today by a wide diversity of forms that range from the 6 meter "wing-span" Manta ray to the 20 centimeter long cigar sharks, from the sluggish wobbegongs of Australia to the high performance open ocean mako's that have burst speeds of 60 k.p.h., and from filter feeders like the whale shark to some of the most effective and notorious predators in the sea like the Great White Shark . The first stage in understanding how the evolutionary process might have shaped such a diversity of form involves understanding the inter-relationships among these animals.

Dr. Naylor's group has been involved in trying to estimate the relationships among living elasmobranchs by contrasting their DNA sequences. This has involved amplifying protein coding sequences from these animals and subjecting the resulting sequences to phylogenetic analysis. This work involves computational modeling of the forces that have shaped the evolution of the proteins themselves and incorporates constraints on evolution imposed by functional and structural demands of the proteins themselves.