Escuela de Medicina Veterinaria, Facultad de Medicina y Ciencias de la Salud, Universidad Mayor, Camino La Pirámide 5750, Huechuraba, Santiago, Chile.
Departamento de Ciencias, Facultad de Artes Liberales, Universidad Adolfo Ibáñez, Santiago, Chile.
Oecologia. 2023 Dec;203(3-4):395-405. doi: 10.1007/s00442-023-05474-y. Epub 2023 Nov 10.
Oxidative status and immune function are energy-demanding traits closely linked to diet composition, particularly resource availability and nutritional value. In seasonal environments, nutrient availability and diet quality fluctuate, potentially influencing these traits. However, limited evidence exists regarding these dietary effects on immune function in seasonal environments. In this study, we employed stable isotope analysis to assess the impact of seasonal changes in niche width and trophic level (i.e., δN) on two immune variables (hemolysis and hemagglutination scores) and two oxidative status parameters (lipid peroxidation and total antioxidant capacity) in three passerine species: Zonotrichia capensis (omnivorous), Troglodytes aedon (insectivorous), and Spinus barbatus (granivorous). We found that hemolysis scores varied seasonally in Z. capensis, with higher values in winter compared to summer. Total antioxidant capacity (TAC) also increased during the winter in Z. capensis and S. barbatus. The isotopic niche width for Z. capensis and S. barbatus was smaller in winter than in summer, with the omnivorous species exhibiting a decrease in δN. Despite the seasonal shifts in ecological and physiological traits in Z. capensis, we identified no correlation between immune response and TAC with trophic level. In contrast, in the granivorous S. barbatus, the lower trophic level resulted in an increase in TAC without affecting immunity. Our findings revealed that dietary shifts do not uniformly impact oxidative status and immune function across bird species, highlighting species-specific responses to seasonal changes. This underscores the importance of integrating ecological and evolutionary perspectives when examining how diet shapes avian immunity and oxidative balance.
氧化状态和免疫功能是与饮食组成密切相关的能量需求特征，特别是资源的可利用性和营养价值。在季节性环境中，营养物质的可利用性和饮食质量会发生波动，这可能会影响这些特征。然而，关于饮食对季节性环境中免疫功能的影响，目前证据有限。在这项研究中，我们使用稳定同位素分析来评估生态位宽度和营养级（即 δN）季节性变化对三种雀形目鸟类的两个免疫变量（溶血和血凝评分）和两个氧化状态参数（脂质过氧化和总抗氧化能力）的影响：Zonotrichia capensis（杂食性）、Troglodytes aedon（食虫性）和 Spinus barbatus（食谷性）。我们发现，Z. capensis 的溶血评分在季节间存在差异，冬季的分值高于夏季。Z. capensis 和 S. barbatus 的总抗氧化能力（TAC）在冬季也有所增加。Z. capensis 和 S. barbatus 的生态位宽度在冬季比夏季更小，杂食性物种的 δN 降低。尽管 Z. capensis 的生态和生理特征在冬季发生了季节性变化，但我们没有发现免疫反应和 TAC 与营养级之间存在相关性。相比之下，在食谷性的 S. barbatus 中，较低的营养级导致 TAC 增加而不影响免疫力。我们的研究结果表明，饮食变化不会在鸟类物种之间均匀地影响氧化状态和免疫功能，突出了物种对季节性变化的特定反应。这强调了在研究饮食如何塑造鸟类免疫和氧化平衡时，纳入生态和进化观点的重要性。
