Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana, USA.
Department of Biology, McNeese State University, Lake Charles, Louisiana, USA.
Sci Rep. 2018 Apr 18;8(1):6174. doi: 10.1038/s41598-018-24579-6.
Many species alter skin color to varying degrees and by different mechanisms. Here, we show that some crocodylians modify skin coloration in response to changing light and environmental conditions. Within the Family, Crocodylidae, all members of the genus Crocodylus lightened substantially when transitioned from dark enclosure to white enclosures, whereas Mecistops and Osteolaemus showed little/no change. The two members of the Family Gavialidae showed an opposite response, lightening under darker conditions, while all member of the Family Alligatoridae showed no changes. Observed color changes were rapid and reversible, occurring within 60-90 minutes. The response is visually-mediated and modulated by serum α-melanocyte-stimulating hormone (α-MSH), resulting in redistribution of melanosomes within melanophores. Injection of crocodiles with α-MSH caused the skin to lighten. These results represent a novel description of color change in crocodylians, and have important phylogenetic implications. The data support the inclusion of the Malayan gharial in the Family Gavialidae, and the shift of the African slender-snouted crocodile from the genus Crocodylus to the monophyletic genus Mecistops.
许多物种在不同程度上通过不同的机制改变皮肤颜色。在这里，我们表明一些鳄形目动物会根据光照和环境条件的变化来调节皮肤颜色。在鳄形目科中，所有的鳄属动物在从黑暗的围栏过渡到白色的围栏时都会明显变浅，而美西鳄属和长吻鳄属的变化很小或没有变化。两个长吻鳄科的成员在较暗的条件下变浅，而所有短吻鳄科的成员都没有变化。观察到的颜色变化是快速和可逆的，在 60-90 分钟内发生。这种反应是视觉介导的，并受血清α-促黑素细胞激素（α-MSH）的调节，导致黑色素细胞内的黑色素重新分布。给鳄鱼注射α-MSH 会导致皮肤变浅。这些结果代表了鳄形目动物颜色变化的新描述，具有重要的系统发育意义。这些数据支持将马来长吻鳄归入长吻鳄科，并将非洲窄吻鳄从鳄属转移到单系的美西鳄属。
