Franco-Belussi Lilian, Provete Diogo Borges, De Oliveira Classius
Department of Biology São Paulo State University (UNESP) São José do Rio PretoSão Paulo Brazil.
Present address: Graduate program in Biotechnology and Environmental monitoring CCTS Federal University of São Carlos Sorocaba São Paulo Brazil.
Ecol Evol. 2017 Oct 3;7(22):9222-9233. doi: 10.1002/ece3.3438. eCollection 2017 Nov.
Internal organs of ectotherms have melanin-containing cells that confer different degrees of coloration to them. Previous experimental studies analyzed their developmental origin, role in immunity, and hormonal regulation. For example, melanin increases with ultraviolet radiation (UV) and temperature in frogs and fish. However, little is known about how environmental variables influence the amount of coloration on organs among amphibian species over a large spatial extent. Here, we tested how climatic variables (temperature, UV, and photoperiod) influence the coloration of internal organs of anurans. We recorded the level of melanin pigmentation using four categories on 12 internal organs and structures of 388 specimens from 43 species belonging to six anuran families. Then, we tested which climatic variables had the highest covariation with the pigmentation on each organ after controlling for spatial autocorrelation in climatic variables and phylogenetic signal in organ coloration using the extended version of the RLQ ordination. Coloration in all organs was correlated with the phylogeny. However, the coloration of different organs was affected by different variables. Specifically, the coloration of the heart, kidneys, and rectum of hylids, , some , and strongly covaried with temperature and photoperiod, whereas that of the testicle, lumbar parietal peritoneum, lungs, and mesenterium of Leiuperinae, Hylodidae, , and most had highest covariation with UV-B and temperature. Our results support the notion that melanin pigmentation on the surface of organs of amphibians has an adaptive function conferred by the protective functions of the pigment. But most importantly, internal melanin seems to respond differently to climatic variables depending on the lineage and locality in which species occur.
变温动物的内脏器官含有含黑色素的细胞，这些细胞赋予它们不同程度的颜色。先前的实验研究分析了它们的发育起源、在免疫中的作用以及激素调节。例如，青蛙和鱼类体内的黑色素会随着紫外线辐射（UV）和温度的升高而增加。然而，在较大空间范围内，关于环境变量如何影响两栖动物物种器官颜色变化的研究却很少。在这里，我们测试了气候变量（温度、紫外线和光周期）如何影响无尾两栖类动物内脏器官的颜色。我们使用四个等级记录了来自六个无尾两栖类科43个物种的388个标本的12个内脏器官和结构的黑色素沉着水平。然后，我们使用RLQ排序的扩展版本，在控制了气候变量的空间自相关和器官颜色的系统发育信号后，测试了哪些气候变量与每个器官的色素沉着具有最高的协变关系。所有器官的颜色都与系统发育相关。然而，不同器官的颜色受到不同变量的影响。具体来说，雨蛙科动物的心脏、肾脏和直肠的颜色变化与温度和光周期密切相关，而细趾蟾科、多指节蟾科的睾丸、腰壁腹膜、肺和肠系膜以及大多数物种的这些器官的颜色变化与UV - B和温度具有最高的协变关系。我们的研究结果支持了这样一种观点，即两栖动物器官表面的黑色素沉着具有由色素的保护功能赋予的适应性功能。但最重要的是，内部黑色素似乎根据物种所处的谱系和地理位置对气候变量做出不同的反应。
