Lu Yuanyuan, Kovalev Alexander, Li Lulu, Li Chuchu, Zhu Xinyi, He Min, Yang Xingke, Bai Ming, Gorb Stanislav N
State Key Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
Department of Functional Morphology and Biomechanics, Zoological Institute, University of Kiel, 24118, Kiel, Germany.
Front Zool. 2025 Aug 4;22(1):18. doi: 10.1186/s12983-025-00571-5.
The phenomenon of color polymorphism has been extensively documented in a range of animal species. A series of hypotheses have been proposed to explain potential functions of color variations in diverse habitats. However, the generation of color is an intricate physical, chemical and biological process. In this instance, the attempts to explain the distribution patterns and their potential causes lacking structural background of color formation, are likely to be misguiding.
Here we studied the distribution pattern of color phenotypes in the beetle Popillia mutans (Insecta: Coleoptera: Rutelinae). Three phenotypes (blue, green and red) are distributed in a not mutually exclusive manner, with the blue phenotype tending to be more prevalent in the cooler northern area, seemingly following Bogert's rule, and the others mainly in the warmer southern area. Subsequent analysis demonstrated that this type of distribution correlates with the environmental factor of temperature. Based on the optical, mechanical and chemical characteristics of the cuticle, we found that this species represents a special case in which melanin layering causes structural coloration, whereas pigmentation plays a primary role in red phenotype and physical coloration is the dominant factor in blue and green phenotypes. However, the structural alterations within the cuticle have no influence on its mechanical properties, different from previously suggested. We have also shown that the blue phenotype exhibits a slightly faster heating rate than the other phenotypes facilitating their adaptation to lower-temperature regions.
Our results elucidate the structural background of color and identify the possible natural selection factor from an evolutionary standpoint. This aids in understanding species formation, as well as prospective dynamic distribution of the phenotypes under the pressure of climate change.
颜色多态性现象在一系列动物物种中已有广泛记载。人们提出了一系列假说来解释不同栖息地中颜色变化的潜在功能。然而，颜色的产生是一个复杂的物理、化学和生物过程。在这种情况下，试图在缺乏颜色形成结构背景的情况下解释分布模式及其潜在原因，很可能会产生误导。
在此，我们研究了甲虫变色花金龟（昆虫纲：鞘翅目：丽金龟科）颜色表型的分布模式。三种表型（蓝色、绿色和红色）并非相互排斥地分布，蓝色表型在较凉爽的北方地区似乎更为普遍，似乎遵循博格特法则，而其他表型主要分布在较温暖的南方地区。随后的分析表明，这种分布类型与温度环境因素相关。基于角质层的光学、力学和化学特性，我们发现该物种代表了一种特殊情况，即黑色素分层导致结构色，而色素沉着在红色表型中起主要作用，物理色在蓝色和绿色表型中占主导因素。然而，角质层内的结构改变对其力学性能没有影响，这与之前的观点不同。我们还表明，蓝色表型的加热速度略快于其他表型，这有助于它们适应低温区域。
我们的结果阐明了颜色的结构背景，并从进化的角度确定了可能的自然选择因素。这有助于理解物种形成，以及气候变化压力下表型的未来动态分布。
