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RESEARCH ARTICLE

Retinal photoreceptor and ganglion cell types and topographies in the red fox (Vulpes vulpes) and Arctic fox (Vulpes lagopus)

Erich Pascal Malkemper

Corresponding Author

E-mail address: pascal.malkemper@uni-due.de

Department of General Zoology, Faculty of Biology, University of Duisburg‐Essen, , Essen, Germany

Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, , Praha 6, Czech Republic

Correspondence

Erich Pascal Malkemper, Department General Zoology, Faculty of Biology, University of Duisburg‐Essen, Universitätsstr. 5, 45117 Essen, Germany.

Email: pascal.malkemper@uni-due.de

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Leo Peichl

Max Planck Institute for Brain Research, , Frankfurt am Main, Germany

Institute of Cellular and Molecular Anatomy, Dr. Senckenbergische Anatomie, Goethe University Frankfurt, , Frankfurt am Main, Germany

Present address Leo Peichl, Institute of Cellular and Molecular Anatomy, Dr. Senckenbergische Anatomie, Goethe University Frankfurt, Frankfurt am Main, GermanySearch for more papers by this author
First published: 12 July 2018

Funding information Grantová Agentura České Republiky, Grant/Award Number: 15‐21840S; German National Academic Foundation

Abstract

The red fox (Vulpes vulpes) is the carnivore with the widest distribution in the world. Not much is known about the visual system of these predominantly forest‐dwelling animals. The closely related Arctic fox (Vulpes lagopus) lives in more open tundra habitats. In search for corresponding adaptations, we examined the photoreceptors and retinal ganglion cells (RGCs), using opsin immunohistochemistry, lucifer yellow injections and Nissl staining. Both species possess a majority of middle‐to‐longwave‐sensitive (M/L) and a minority of shortwave‐sensitive (S) cones, indicating dichromatic color vision. Area centralis peak cone densities are 22,600/mm2 in the red fox and 44,800/mm2 in the Arctic fox. Both have a centro‐peripheral density decrease of M/L cones, and a dorsoventrally increasing density of S cones. Rod densities and rod/cone ratios are higher in the red fox than the Arctic fox. Both species possess the carnivore‐typical alpha and beta RGCs. The RGC topography shows a centro‐peripheral density gradient with a distinct area centralis (mean peak density 7,900 RGCs/mm2 in the red fox and 10,000 RGCs/mm2 in the Arctic fox), a prominent visual streak of higher RGC densities in the Arctic fox, and a moderate visual streak in the red fox. Visual acuity and estimated sound localization ability were nearly identical between both species. In summary, the red fox retina shows adaptations to nocturnal activity in a forest habitat, while the Arctic fox retina is better adapted to higher light levels in the open tundra.