title: Evidence of light-dependent magnetic compass orientation in urodele amphibian larvae.
abstract: Experiments were conducted to investigate whether larval palmate newts undertake orientation toward or away from the home shoreline (y-axis orientation) using the geomagnetic field to steer the most direct route, and if they accomplish this task through a light-dependent magnetoreception mechanism similar to that found in anuran tadpoles and adult newts. Larval palmate newts trained and then tested under full-spectrum light showed bimodal magnetic compass orientation that coincided with the magnetic direction of the trained y-axis. In contrast, larvae trained under long-wavelength (≥500nm) light and then tested under full-spectrum light displayed bimodal orientation perpendicular to the trained y-axis direction. These results offer evidence for the use of magnetic compass cues in orienting urodele amphibian larvae, and provide additional support for the light-dependent magnetoreception mechanism since they are in complete agreement with earlier studies showing that the observed 90° shift in the direction of magnetic compass orientation under long-wavelength light (≥500nm) is due to a direct effect of light on the underlying magnetoreception mechanism. This study is the first to provide evidence of a light-dependent magnetic compass in larval urodeles.
authors.affiliation: Departamento de Biología Animal, Universidad de Salamanca, Campus Miguel de Unamuno, Edificio de Farmacia 5ª Planta, 37007 Salamanca, Spain. Electronic address: fjdiego@herpetologica.org.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Diego-Rasilla
authors.affiliation: Gabinete de Iniciativas Socioculturales y de Formación S.L., Calle Nicaragua 7, 37003 Salamanca, Spain. Electronic address: romiluengo@cop.es.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Luengo
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA. Electronic address: jphillip@vt.edu.
authors.forename: John B
authors.initials: JB
authors.lastname: Phillips
mesh_terms: D000818:Animals; D007814:Larva / Q000502:physiology; D008027:Light; D060526:Magnetic Fields; D008280:Magnetics; D009949:Orientation / Q000502:physiology; D012455:Salamandridae / Q000502:physiology*
keywords: Light-dependent magnetoreception; Lissotriton helveticus; Magnetic compass; Urodele; Y-axis orientation