RETINAL PROJECTIONS IN TELEOST FISHES - PATTERNS, VARIATIONS, AND QUESTIONS

1. Variations in the pathways of fibers and in the morphology of nuclei in the central nervous system can be used to infer evolutionary changes. 2. Within the large and diverse radiation of ray-finned fishes, variations in the visual system-including the paths of ipsilaterally projecting fibers, the distribution of retinopetal cells, the geometry of homologous nuclei relative to topographically mapped projections, the relative size of homologous nuclei, the structure of the optic tectum, and even an evolutionarily novel nucleus-have been found. 3. Such differences, particularly those occurring between relatively closely related taxa, may lend themselves to studies of the underlying mechanisms for evolutionary change in the central nervous system and may eventually lead to identification of ecologically related niche behaviors and adaptations.