Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer
Permanent lenke
https://hdl.handle.net/10037/25073Dato
2013-12-22Type
Journal articleTidsskriftartikkel
Peer reviewed
Forfatter
Stokkan, Karl-Arne; Folkow, Lars; Dukes, Juliet; Neveu, Magella; Hogg, Chris R; Siefken, Sandra Katharina Christiane; Dakin, Steven C; Jeffery, GlenSammendrag
Arctic reindeer experience extreme changes in environmental light from
continuous summer daylight to continuous winter darkness. Here, we
show that they may have a unique mechanism to cope with winter darkness
by changing the wavelength reflection from their tapetum lucidum (TL). In
summer, it is golden with most light reflected back directly through the
retina, whereas in winter it is deep blue with less light reflected out of the
eye. The blue reflection in winter is associated with significantly increased
retinal sensitivity compared with summer animals. The wavelength of reflection depends on TL collagen spacing, with reduced spacing resulting in
shorter wavelengths, which we confirmed in summer and winter animals.
Winter animals have significantly increased intra-ocular pressure, probably
produced by permanent pupil dilation blocking ocular drainage. This may
explain the collagen compression. The resulting shift to a blue reflection
may scatter light through photoreceptors rather than directly reflecting it,
resulting in elevated retinal sensitivity via increased photon capture. This
is, to our knowledge, the first description of a retinal structural adaptation
to seasonal changes in environmental light. Increased sensitivity occurs at
the cost of reduced acuity, but may be an important adaptation in reindeer
to detect moving predators in the dark Arctic winter.
Forlag
The Royal SocietySitering
Stokkan k.a., Folkow P., Dukes, Neveu M, Hogg CR, Siefken SKC, Dakin, Jeffery G. Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer. Proceedings of the Royal Society of London. Biological Sciences. 2013;280(1773)Metadata
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Copyright 2013 The Author(s)