Rapid Evolution of the Visual System: a Cellular Assay of the Retina and Dorsal Lateral Geniculate Nucleus of the Spanish Wildcat and the Domestic Cat
The Journal of Neuroscience, January 1993, 13(l): 208-229 Rapid Evolution of the Visual System: A Cellular Assay of the Retina and Dorsal Lateral Geniculate Nucleus of the Spanish Wildcat and the Domestic Cat Robert W. Williams,’ Carmen Cavada,2 and Fernando Reinoso-Suhrez* ‘Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee, Memphis, Tennessee 38163 and *Departamento de Morfologia, Facultad de Medicina, Universidad Aut6noma de Madrid, 28029 Madrid, Spain The large Spanish wildcat, Fe/is silvestris tartessia, has re- and important topic, it has been difficult to study the process tained features of the Pleistocene ancestor of the modern of brain evolution in any detail. Our approach has been to domestic cat, F. catus. To gauge the direction and magnitude identify a pair of closely related living species,one from a highly of short-term evolutionary change in this lineage, we have conservative branch that has retained near identity with the compared the retina, the optic nerve, and the dorsal lateral ancestral species,and the other from a derived branch that has geniculate nucleus (LGN) of Spanish wildcats and their do- undergone rapid evolutionary change. The recent recognition mestic relatives. Retinas of the two species have the same that evolution and speciationcan occur in short bursts separated area. However, densities of cone photoreceptors are higher by long interludes of stasisprovides a sound theoretical basis in wildcat-over 100% higher in the area centralis-where- for a search for such pairs (Schindewolf, 1950; Eldredge and as rod densities are as high, or higher, in the domestic lin- Gould, 1972; Stanley, 1979; Gould and Eldredge, 1986).
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