Roth Lina S V, Kelber Almut
University of Lund, Department of Cell and Organism Biology, Vision Group, Helgonavägen 3, S-223 62 Lund, Sweden.
Proc Biol Sci. 2004 Dec 7;271 Suppl 6(Suppl 6):S485-7. doi: 10.1098/rsbl.2004.0227.
Nocturnal animals are said to sacrifice colour vision in favour of increased absolute sensitivity. This is true for most vertebrates that possess a dual retina with a single type of rod for colour-blind night vision and multiple types of cone for diurnal colour vision. However, among the nocturnal vertebrates, geckos are unusual because they have no rods but three cone types. Here, we show that geckos use their cones for colour vision in dim light. Two specimens of the nocturnal helmet gecko Tarentola (formerly Geckonia) chazaliae were able to discriminate blue from grey patterns by colour alone. Experiments were performed at 0.002 cd m(-2), a light intensity similar to dim moonlight. We conclude that nocturnal geckos can use cone-based colour vision at very dim light levels when humans rely on colour-blind rod vision.
夜行性动物据说为了提高绝对敏感度而牺牲了色觉。对于大多数拥有双重视网膜的脊椎动物来说确实如此，它们有单一类型的视杆细胞用于色盲的夜视，以及多种类型的视锥细胞用于日间色觉。然而，在夜行性脊椎动物中，壁虎很不寻常，因为它们没有视杆细胞，却有三种视锥细胞类型。在这里，我们表明壁虎在昏暗光线下利用它们的视锥细胞进行色觉。夜行性头盔壁虎（原壁虎属）查扎利亚壁虎的两个标本能够仅通过颜色区分蓝色和灰色图案。实验是在0.002坎德拉每平方米的光强度下进行的，这一光强度类似于昏暗的月光。我们得出结论，当人类依靠色盲的视杆细胞视觉时，夜行性壁虎在非常昏暗的光线下可以利用基于视锥细胞的色觉。
