title: Historical perspective on the development and evolution of eyes and photoreceptors.
abstract: The development and evolution of eyes is an "old problem" in biology, which required a special treatment in Charles Darwin's "Origin of the species" (1882) under the heading of "Difficulties of the theory". Darwin postulated a simple and imperfect eye, as a prototype, which can vary and evolve under natural selection into more complex and perfect eyes. Based upon morphological criteria and the different modes of development of the different kinds of eyes, neodarwinists have postulated that the various eye-types are polyphyletic in origin and that the eyes have evolved independently in the various animal phyla. Recent developmental genetic experiments and molecular phylogenetic analyses cast serious doubts on this interpretation and argue strongly for a monophyletic origin of the eyes from a Darwinian prototype and subsequent divergent, parallel and convergent evolution leading to the various eye-types.
authors.affiliation: Dept. Cell Biology, Biozentrum, University of Basel, Switzerland. walter.gehring@unibas.ch
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Gehring
mesh_terms: D000818:Animals; D004330:Drosophila / Q000033:anatomy & histology / Q000196:embryology; D019143:Evolution, Molecular; D005123:Eye / Q000196:embryology*; D005136:Eye Proteins / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D008027:Light; D008855:Microscopy, Electron, Scanning; D008953:Models, Anatomic; D008954:Models, Biological; D009799:Ocular Physiological Phenomena; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D010786:Photoreceptor Cells / Q000737:chemistry; D017956:Photoreceptor Cells, Invertebrate / Q000196:embryology*; D010802:Phylogeny; D012097:Repressor Proteins / Q000378:metabolism; D014319:Triturus / Q000033:anatomy & histology*
chemical_list: D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D049452:Green Fluorescent Proteins