Evidence of light-dependent magnetic compass orientation in urodele amphibian larvae

摘要

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 (>= 500 nm) 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 (>= 500 nm) 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. (C) 2015 Elsevier B.V. All rights reserved.