Stable Isotope Laboratory, Institute for Limnology, University of Constance, Constance, Germany.
Oecologia. 2011 Dec;167(4):937-42. doi: 10.1007/s00442-011-2041-x. Epub 2011 Jun 14.
It is widely accepted that stable isotope ratios in inert tissues such as feather keratin reflect the dietary isotopic signature at the time of the tissue synthesis. However, some elements such as stable nitrogen isotopes can be affected by individual physiological state and nutritional stress. Using malaria infection experiment protocols, we estimated the possible effect of malaria parasite infections on feather carbon (δ(13)C) and nitrogen (δ(15)N) isotope signatures in juvenile common crossbills Loxia curvirostra. The birds were experimentally infected with Plasmodium relictum (lineage SGS1) and P. ashfordi (GRW2), two widespread parasites of passerines. Experimental birds developed heavy parasitemia of both parasites and maintained high levels throughout the experiment (33 days). We found no significant difference between experimental and control birds in both δ(13)C and δ(15)N values of feathers re-grown. The study shows that even heavy primary infections of malaria parasites do not affect feather δ(13)C and δ(15)N isotopic signatures. The results of this experiment demonstrate that feather isotope values of wild-caught birds accurately reflect the dietary isotopic sources at the time of tissue synthesis even when the animal's immune system might be challenged due to parasitic infection.
人们普遍认为，惰性组织（如羽毛角蛋白）中的稳定同位素比值反映了组织合成时的饮食同位素特征。然而，一些元素，如稳定的氮同位素，可能会受到个体生理状态和营养压力的影响。本研究使用疟疾感染实验方案，估计疟疾寄生虫感染对幼年普通朱雀（Loxia curvirostra）羽毛碳（δ(13)C）和氮（δ(15)N）同位素特征的可能影响。实验中鸟类感染了广泛存在于雀形目动物中的疟原虫 Plasmodium relictum（SGS1 谱系）和 P. ashfordi（GRW2）。实验鸟类的两种寄生虫均出现严重的寄生虫血症，且在整个实验过程中（33 天）一直保持高水平。我们发现，实验组和对照组鸟类的羽毛再生的 δ(13)C 和 δ(15)N 值之间没有显著差异。本研究表明，即使是严重的疟原虫原发性感染也不会影响羽毛 δ(13)C 和 δ(15)N 同位素特征。该实验结果表明，即使动物的免疫系统因寄生虫感染而受到挑战，野生鸟类的羽毛同位素值仍能准确反映组织合成时的饮食同位素来源。
