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P.K. Ahnelt, C. Schubert, A. Kuebber–Heiss, E.M. Anger; Adaptive Design in Felid Retinal Cone Topographies . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4540.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Data on the visual capacities of large and endangered Felid species are sparse, while the domestic cat has served as a mammalian model to study retinal circuitry from photoreceptors to ganglion cells. We have gathered eyes from 7 felid species to compare their retinal cone photoreceptor topography and discuss its correlation to specific lifestyles and habitats. Methods: We have studied eyes from cheetah (Acinonyx jubatus), lion (Leo panthera), tiger (Panthera tigris), jaguar (P. onca), Siberian manuls (Otocolobus manul), Eurasean lynx (Lynx lynx) and domestic cats (Felis ) obtained during autopsy of animals delivered to veterinary pathology from animal parks and zoos. Spectral cone subpopulations were identified and mapped using antisera JH–492 for M–opsin, JH455 and sc–14363 (Santa Cruz) for S–opsin. Results: All species have central areas located in the superior temporal quadrant but the cheetah deviates strongly in many parameters: In spite of smaller eye diameter the Cheetah has total the highest cone numbers (9,5 Mio M–cones +1,5 Mio S–cones, as compared to 5,5 + 1,5 Mio in tiger), Cheetah maximum density values reach 41000 M– + 6000 S–cones/mm², as compared to 17000/1300 in Lynx. A prominent visual streak is present with vertical /horizontal accumulated cone ratios of ca. 0,7 and the papillary temporal/nasal meridional ratio for Cheetah is 1,5 (for cat: 0,9). Cheetah overall S–cone proportion is14% as compared to tiger/lion (8%/10%). Conclusions: The cheetah's visual organization is exceptional among felids confirming the species' specialized adaptation as a diurnal open–terrain speed hunter. In other species features tend to correlate with species size (dorso–ventral a/symmetry), terrestrial versus semi–arboreal behaviour (elongated versus concentric gradients) and open–closed habitat differences. The lower degree of topographic specialization in most felids indicates that their visual design is shaped by an interplay of parameters which more closely resemble the basic feline eco–type. Their differentiation will require further data and functional studies from these and other felid species.
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