Pearson Scott F, Levey Douglas J, Greenberg Cathryn H, Martínez Del Rio Carlos
Department of Zoology, University of Florida, Gainesville, FL 32611-8525, USA.
Oecologia. 2003 May;135(4):516-23. doi: 10.1007/s00442-003-1221-8. Epub 2003 Mar 28.
The use of stable isotopes to infer diet requires quantifying the relationship between diet and tissues and, in particular, knowing of how quickly isotopes turnover in different tissues and how isotopic concentrations of different food components change (discriminate) when incorporated into consumer tissues. We used feeding trials with wild-caught yellow-rumped warblers (Dendroica coronata) to determine delta15N and delta13C turnover rates for blood, delta15N and delta13C diet-tissue discrimination factors, and diet-tissue relationships for blood and feathers. After 3 weeks on a common diet, 36 warblers were assigned to one of four diets differing in the relative proportion of fruit and insects. Plasma half-life estimates ranged from 0.4 to 0.7 days for delta13C and from 0.5 to 1.7 days for delta15N . Half-life did not differ among diets. Whole blood half-life for delta13C ranged from 3.9 to 6.1 days. Yellow-rumped warbler tissues were enriched relative to diet by 1.7-3.6% for nitrogen isotopes and by -1.2 to 4.3% for carbon isotopes, depending on tissue and diet. Consistent with previous studies, feathers were the most enriched and whole blood and plasma were the least enriched or, in the case of carbon, slightly depleted relative to diet. In general, tissues were more enriched relative to diet for birds on diets with high percentages of insects. For all tissues, carbon and nitrogen isotope discrimination factors increased with carbon and nitrogen concentrations of diets. The isotopic signature of plasma increased linearly with the sum of the isotopic signature of the diet and the discrimination factor. Because the isotopic signature of tissues depends on both elemental concentration and isotopic signature of the diet, attempts to reconstruct diet from stable isotope signatures require use of mixing models that incorporate elemental concentration.
利用稳定同位素推断饮食需要量化饮食与组织之间的关系，特别是要了解同位素在不同组织中的周转速度，以及不同食物成分在纳入消费者组织时其同位素浓度如何变化（分馏）。我们对野生捕获的黄腰林莺（Dendroica coronata）进行了饲养试验，以确定血液中δ15N和δ13C的周转速率、δ15N和δ13C的饮食 - 组织分馏因子，以及血液和羽毛的饮食 - 组织关系。在共同饮食3周后，36只林莺被分配到四种饮食中的一种，这四种饮食在水果和昆虫的相对比例上有所不同。血浆半衰期估计值对于δ13C为0.4至0.7天，对于δ15N为0.5至1.7天。半衰期在不同饮食之间没有差异。全血中δ13C的半衰期为3.9至6.1天。黄腰林莺的组织相对于饮食，氮同位素富集1.7 - 3.6%，碳同位素富集 - 1.2至4.3%，这取决于组织和饮食。与先前的研究一致，相对于饮食，羽毛的富集程度最高，全血和血浆的富集程度最低，或者就碳而言，相对于饮食略有贫化。一般来说，对于食用高比例昆虫饮食的鸟类，其组织相对于饮食的富集程度更高。对于所有组织，碳和氮同位素分馏因子随着饮食中碳和氮浓度的增加而增加。血浆的同位素特征随着饮食的同位素特征与分馏因子之和呈线性增加。由于组织的同位素特征取决于饮食的元素浓度和同位素特征，因此试图从稳定同位素特征重建饮食需要使用纳入元素浓度的混合模型。
