title: Orientation to the sun by animals and its interaction with crypsis.
abstract: Orientation with respect to the sun has been observed in a wide range of species and has generally been interpreted in terms of thermoregulation and/or ultraviolet (UV) protection. For countershaded animals, orientation with respect to the sun may also result from the pressure to exploit the gradient of coloration optimally to enhance crypsis.Here, we use computational modelling to predict the optimal countershading pattern for an oriented body. We assess how camouflage performance declines as orientation varies using a computational model that incorporates realistic lighting environments.Once an optimal countershading pattern for crypsis has been chosen, we determine separately how UV protection/irradiation and solar thermal inflow fluctuate with orientation.We show that body orientations that could optimally use countershading to enhance crypsis are very similar to those that allow optimal solar heat inflow and UV protection.Our findings suggest that crypsis has been overlooked as a selective pressure on orientation and that new experiments should be designed to tease apart the respective roles of these different selective pressures. We propose potential experiments that could achieve this.
authors.affiliation: School of Psychology and Neuroscience University of St Andrews South Street St Andrews Fife KY16 9JP UK.
authors.forename: Olivier
authors.initials: O
authors.lastname: Penacchio
authors.affiliation: School of Biological Sciences Life Sciences Building 24 Tyndall Avenue Bristol BS8 1TQ UK.
authors.forename: Innes C
authors.initials: IC
authors.lastname: Cuthill
authors.affiliation: School of Psychology and Neuroscience University of St Andrews South Street St Andrews Fife KY16 9JP UK; Division of Psychology Social and Health Sciences Abertay University Dundee DD1 1HG UK.
authors.forename: P George
authors.initials: PG
authors.lastname: Lovell
authors.affiliation: School of Biology Dyers Brae University of St Andrews St Andrews Fife KY16 9TH UK.
authors.forename: Graeme D
authors.initials: GD
authors.lastname: Ruxton
authors.affiliation: School of Psychology and Neuroscience University of St Andrews South Street St Andrews Fife KY16 9JP UK.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Harris
keywords: body orientation; camouflage; countershading; crypsis; thermal melanism; thermoregulation; ultraviolet protection