Evolution of sensory pathways in vertebrates.

Sensory receptor evolution is a function of the array of events in the physical world that are detectable by biological systems. Examples of both conservation and innovation occur across vertebrates in the organization of sensory systems for the reception of photic, positional, chemical, tactile, mechanosensory and electrosensory lateral line, acoustic, and magnetic stimuli. Recent findings in genetics and ontogeny allow new approaches to questions of how new sensory receptors and their corresponding central nervous system pathways evolve, how sensory specialization arises and its effects on other sensory systems, the role of cell-adhesion molecules in the ontogeny of sensory pathways and their topological organization, and the occurrence of reorganization and co-option of developmental modules over sensory system evolution. Relatively simple alterations at the genetic and ontogenetic levels often can result in alterations in the phenotype of far greater complexity.