Prof. Dr. Almut Kelber
Lund University, Schweden
Faculty of Science – Fuctional Zoology
Donnerstag 22.09.2016
Dauer: 51:26 min
Abstract
In bright sunlight, we see the world in sparkling colours, but when night falls, colours fade away until, with less than a half moon, everything appears in 50 shades of grey. The reason for this colour vision lies in our duplex retina with three types of cones – noisy photoreceptors – and only one type of rods – receptors optimized for low noise. Colour discrimination is based on comparison of cone signals, and limited by receptor noise. Over a large intensity range, the level of receptor noise stays constant, but in dim light, photon shot noise statrts impairing colour discrimination, and the absolute threshold of cone-based vision is set by dark noise in cones. Like humans, other vertebrates with duplex retinae use colour-blind rod vision in dim light.
Nocturnal insects and vertebrates lacking rods have to use the same set of receptors day and night. They have evolved adaptations to increase the sensitivity of their eyes and photoreceptors, and to reduce receptor noise. This allows them to use chromatic vision in dimmer light intensities than humans. Frogs and toads that have two types of rod use opponent signals from rods to control phototaxis even at their visual threshold, at light intensities ten times darker than the absolute threshold of human vision. However, for tasks such as prey or mate choice, their colour discrimination abilities fail at brighter light intensities, only ten times darker than the humans colour vision threshold, limited by the dark noise in their cones.
In this presentation, I review what is known about dim-light colour vision and compare colour vision thresholds with the optical sensitivity of the photoreceptors in selected animal species with lens and compound eyes.
Biographie
Studium der Biologie an den Universitäten von Mainz, Sussex und Tübingen, Promotion in Tübingen über die Orientierung von Bienen. Nach Aufenthalten in Brasilien und Australien seit 1998 an der Universität Lund, da seit 2007 Professor für Sinnesbiologie. Innerhalb dieses Feldes untersucht Almut Kelber seit Jahren das Farbensehen verschiedener Tiere, darunter Schmetterlinge, Bienen, Vögel, Pferde und Seehunde. Besonderer Fokus liegt auf der Suche nach den Begrenzungen und den Anpassungen des Sehsystems an das Verhalten einer Art sowie and verschiendene ökologische Faktoren wie etwas die Lichtverhältnisse.
Homepage Prof. Dr. Almut Kelber
Farbe im Kopf – Von der Wahrnehmung zur Kunst
Interdisziplinäre Konferenz Institut für Medienwissenschaft und Forschungsinstitut für Augenheilkunde der Eberhard Karls Universität Tübingen mit dem Deutschen Farbenzentrum e.V. – Zentralistitut für Farbe in Wissenschaft und Gestaltung
