Ronanki Shivani, Hegemann Arne, Eikenaar Cas
Department of Biology Lund University Lund Sweden.
Division of Toxicology Wageningen University and Research Wageningen The Netherlands.
Ecol Evol. 2024 Jun 25;14(6):e11516. doi: 10.1002/ece3.11516. eCollection 2024 Jun.
Migratory birds may either upregulate their immune system during migration as they might encounter novel pathogens or downregulate their immune system as a consequence of trade-offs with the resource costs of migration. Support for the latter comes not least from a study that reports a positive correlation in autumn migrating birds between fuel stores and parameters of innate and acquired immune function, that is, energy-exhausted migrants appear to have lowered immune function. However, to our knowledge, no study has tested whether this pattern exists in spring migrating birds, which may face other trade-offs than autumn migrants. Here, we investigate if in spring there is a relationship between fuel stores and microbial-killing ability, a measure of innate immune function, and total immunoglobulin (IgY), a measure of acquired immune function, in four migrating bird species: chaffinches (), dunnocks (), song thrushes () and northern wheatears (). Our findings indicate no significant correlation between fuel stores and either microbial killing ability or IgY levels when considering all species collectively. When analysing species separately, we found a significant negative correlation between fuel stores and microbial-killing ability in chaffinches and a positive correlation between fuel stores and IgY levels in wheatears. In song thrushes, but not in any of the other species, there was a significant negative correlation between relative arrival date and microbial-killing ability and between arrival date and IgY levels. Sex did not affect immune function in any of the species. Our study suggests that the relationship between immune function and fuel stores may be different during spring migration compared to autumn migration. Differences in the speed of migration or pathogen pressure may result in different outcomes of the resource trade-off between investment in immune function and migration among the seasons.
候鸟在迁徙过程中，可能会因为接触到新病原体而增强自身免疫系统，也可能因迁徙资源成本的权衡而抑制免疫系统。对后者的支持尤其来自一项研究，该研究报告称，秋季迁徙鸟类的脂肪储备与先天免疫和后天免疫功能参数之间存在正相关，也就是说，能量耗尽的候鸟似乎免疫功能较低。然而，据我们所知，尚无研究测试这种模式是否存在于春季迁徙鸟类中，因为春季迁徙鸟类可能面临与秋季迁徙鸟类不同的权衡。在这里，我们调查了在春季，四种迁徙鸟类——苍头燕雀、鹪鹩、歌鸫和白斑黑石鵖的脂肪储备与微生物杀灭能力（一种先天免疫功能的指标）以及总免疫球蛋白（IgY，一种后天免疫功能的指标）之间是否存在关联。我们的研究结果表明，当将所有物种综合考虑时，脂肪储备与微生物杀灭能力或IgY水平之间没有显著相关性。当分别分析各个物种时，我们发现苍头燕雀的脂肪储备与微生物杀灭能力之间存在显著负相关，而白斑黑石鵖的脂肪储备与IgY水平之间存在正相关。在歌鸫中，相对到达日期与微生物杀灭能力之间以及到达日期与IgY水平之间存在显著负相关，但在其他任何物种中均未发现这种情况。性别对任何物种的免疫功能均无影响。我们的研究表明，与秋季迁徙相比，春季迁徙期间免疫功能与脂肪储备之间的关系可能有所不同。迁徙速度或病原体压力的差异可能导致不同季节在免疫功能投资与迁徙之间的资源权衡产生不同结果。
