Equipe Ecologie Evolutive, UMR CNRS 6282 Biogéosciences, Université de Bourgogne-Franche Comté, Dijon, France.
PLoS One. 2020 Apr 15;15(4):e0231247. doi: 10.1371/journal.pone.0231247. eCollection 2020.
Carotenoids are diverse lipophilic natural pigments which are stored in variable amounts by animals. Given the multiple biological functions of carotenoids, such variation may have strong implications in evolutionary biology. Crustaceans such as Gammarus amphipods store large amounts of these pigments and inter-population variation occurs. While differences in parasite selective pressure have been proposed to explain this variation, the contribution of other factors such as genetic differences in the gammarid ability to assimilate and/or store pigments, and the environmental availability of carotenoids cannot be dismissed. This study investigates the relative contributions of the gammarid genotype and of the environmental availability of carotenoids in the natural variability in carotenoid storage. It further explores the link of this natural variability in carotenoid storage with major crustacean immune parameters. We addressed these aspects using the cryptic diversity in the amphipod crustacean Gammarus fossarum and a diet supplementation protocol in the laboratory. Our results suggest that natural variation in G. fossarum storage of dietary carotenoids results from both the availability of the pigments in the environment and the genetically-based ability of the gammarids to assimilate and/or store them, which is associated to levels of stimulation of cellular immune defences. While our results may support the hypothesis that carotenoids storage in this crustacean may evolve in response to parasitic pressure, a better understanding of the specific roles of this large pigment storage in the crustacean physiology is needed.
类胡萝卜素是多样化的亲脂性天然色素，动物会以不同的量储存这些色素。鉴于类胡萝卜素具有多种生物学功能，这种变化可能在进化生物学中具有重要意义。例如，十足目甲壳动物（如淡水长臂虾属的桡足类）会大量储存这些色素，并且存在种群间的变异。虽然寄生虫选择压力的差异被认为可以解释这种变异，但其他因素的贡献，如 gammarid 同化和/或储存色素的遗传差异，以及类胡萝卜素的环境可用性，也不能被忽视。本研究调查了 gammarid 基因型和类胡萝卜素环境可用性对色素储存自然变异性的相对贡献。它进一步探讨了这种色素储存自然变异性与主要甲壳动物免疫参数之间的联系。我们使用淡水长臂虾属的隐种多样性和实验室中的饮食补充方案来解决这些方面的问题。我们的结果表明，G. fossarum 对饮食类胡萝卜素的储存自然变异既来自于环境中色素的可用性，也来自于 gammarid 基于遗传的同化和/或储存它们的能力，这与细胞免疫防御的刺激水平有关。虽然我们的结果可能支持这样的假设，即这种甲壳动物的类胡萝卜素储存可能是对寄生虫压力的进化反应，但需要更好地了解这种大型色素储存在甲壳动物生理学中的具体作用。
