Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
Center for Language Evolution Studies, Nicolaus Copernicus University, Toruń, Poland.
Sci Rep. 2024 Nov 24;14(1):29115. doi: 10.1038/s41598-024-80643-4.
Primates, the most colorful mammalian radiation, have previously served as an interesting model to test the functions and evolutionary drivers of variation in eye color. We assess the contribution of photo-regulatory and communicative functions to the external eye appearance of nine macaque species representing all the branches of their radiation. Macaques' well described social structure and wide geographical distribution make them interesting to explore. We find that (1) the posterior option of the anterior eyeball is more pigmented closer to the equator, suggesting photoprotective functions. We also find that (2) the temporal side of the eyeball is more heavily pigmented than the nasal side. This suggests that eyeball pigmentation in macaques is distributed to reduce damage to the corneal limbus. The inclusion of a translocated population of M. fuscata in our analyses also suggests that external eye appearance may change quickly, perhaps owing to phenotypic plasticity. We find no evidence that communicative functions drive variation in external eye appearance in macaques. These results suggest that the amount of light in a species' environment drives variation in eye coloration across macaque species. Furthermore, the geographical distribution of macaques hints at important factors that have yet to be accounted for, such as the reflectivity of the terrain a given species inhabits.
灵长目动物是哺乳动物中最丰富多彩的辐射群，它们之前一直被用作测试眼睛颜色变化的功能和进化驱动因素的有趣模型。我们评估了光调节和通讯功能对代表其辐射所有分支的 9 种猕猴物种的外部眼睛外观的贡献。猕猴具有描述详尽的社会结构和广泛的地理分布，这使得它们成为探索的有趣对象。我们发现：（1）靠近赤道的前眼球后选项色素沉着更多，表明具有光保护功能。我们还发现：（2）眼球的颞侧比鼻侧色素沉着更重。这表明猕猴的眼球色素沉着分布可减少对角膜缘的损伤。我们的分析还包括一个已迁移的猕猴种群，这表明外部眼睛外观可能会迅速变化，可能是由于表型可塑性。我们没有发现通讯功能驱动猕猴外部眼睛外观变化的证据。这些结果表明，物种环境中的光量会驱动猕猴物种之间的眼睛颜色变化。此外，猕猴的地理分布暗示着还有一些重要因素尚未得到解释，例如某个物种栖息的地形的反射率。
