Dipartimento di Biologia ed Evoluzione, Università di Ferrara, Via Borsari 46, Ferrara, 44121, Italy.
J Exp Biol. 2010 Jun 15;213(Pt 12):2048-54. doi: 10.1242/jeb.040246.
The present study first examined whether ruin lizards Podarcis sicula are able to orientate using the e-vector direction of polarized light. Ruin lizards were trained and tested indoors, inside a hexagonal Morris water maze, positioned under an artificial light source producing plane polarized light with a single e-vector, which provided an axial cue. Lizards were subjected to axial training by positioning two identical goals in contact with the centre of two opposite side walls of the Morris water maze. Goals were invisible because they were placed just beneath the water surface, and water was rendered opaque. The results showed that the directional choices of lizards meeting learning criteria were bimodally distributed along the training axis, and that after 90 deg rotation of the e-vector direction of polarized light the lizards directional choices rotated correspondingly, producing a bimodal distribution which was perpendicular to the training axis. The present results confirm in ruin lizards results previously obtained in other lizard species showing that these reptiles can use the e-vector direction of polarized light in the form of a sky polarization compass. The second step of the study aimed at answering the still open question of whether functioning of a sky polarization compass would be mediated by the lizard parietal eye. To test this, ruin lizards meeting learning criteria were tested inside the Morris water maze under polarized light after their parietal eyes were painted black. Lizards with black-painted parietal eyes were completely disoriented. Thus, the present data show for the first time that the parietal eye plays a central role in mediating the functioning of a putative sky polarization compass of lizards.
本研究首先考察了穴居蝾螈是否能够利用偏振光的 e-矢量方向进行定位。穴居蝾螈在室内的六边形 Morris 水迷宫中接受训练和测试，该迷宫位于产生具有单一 e-矢量的平面偏振光的人工光源下，提供了一个轴向线索。通过将两个相同的目标放置在 Morris 水迷宫的两个相对侧壁的中心接触，对蜥蜴进行轴向训练。目标是不可见的，因为它们被放置在水面以下，并且水变得不透明。结果表明，符合学习标准的蜥蜴的定向选择沿训练轴呈双峰分布，并且在偏振光的 e-矢量方向旋转 90 度后，蜥蜴的定向选择相应地旋转，产生与训练轴垂直的双峰分布。本研究结果证实了先前在其他蜥蜴物种中获得的结果，表明这些爬行动物可以利用天空偏振罗盘的偏振光 e-矢量方向。研究的第二步旨在回答一个尚未解决的问题，即天空偏振罗盘的功能是否会由蜥蜴的顶眼介导。为了测试这一点，在 Morris 水迷宫中对符合学习标准的穴居蝾螈进行了测试，这些蜥蜴的顶眼被涂黑后处于偏振光下。顶眼被涂黑的蜥蜴完全迷失了方向。因此，本研究数据首次表明，顶眼在介导蜥蜴假设的天空偏振罗盘的功能方面发挥着核心作用。
