Mixing models in analyses of diet using multiple stable isotopes: a critique
Mixing models in analyses of diet using multiple stable isotopes: a critique
复制标题
DOI：
10.1007/s004420000571
复制
发表时间：
2001-01-01
期刊：
影响因子：
2.7
通讯作者：
Phillips, DL
中科院分区：
文献类型：
--
作者：
Phillips, DL
稳定同位素分析经常用于确定不同食物来源对动物饮食的相对贡献（霍布森1999）。测定了动物组织及其每种潜在食物来源的同位素比值。动物组织的比例与单个食物来源的比例相似（在消化和同化过程中校正分馏后），这说明了它们在饮食中的相对重要性;换句话说，”你吃什么，你就是什么”（DeNiro和Epstein，1978）。两种食物来源可以使用单一元素的同位素比（例如，813 C）进行划分，或者三种食物来源可以使用两种元素的同位素比（例如，513 C和d15？）(Kwak和Zedler 1997）。最近的一些论文使用几何程序来量化的贡献，三种食物来源的饮食使用5I 3C和d15？（Ben-David等，1997 a，1997 b; Kline等，1993; Szepanski等，1999; Whitledge和Rabeni，1997）。然而，这些方法没有提供正确的解决方案，这三个端元混合问题。本文的目的是指出这些方法的缺点，并提出一种替代程序，避免它们。图1显示了分析情况的图形表示。膳食同位素组成由三角形内的点D表示，三角形由调整的食物源同位素组成A '、B 1和C的点界定。在几何过程中，计算线段DA '、DB\和DC的欧几里得距离，并用于计算饮食贡献。已经使用了这种计算的几种变型。Kline等人（1993）使用了以下公式：- .？{DA!+ DB '+ DC）-OX\yt^？
Stable isotope analysis is used frequently to determine the relative contributions of different food sources to an animars diet (Hobson 1999). Isotopie ratios for the animal tissues and each of its potential food sources are de-termined. The similarity of the ratios for the animal tissues with those of individual food sources (after correct-ing for fractionation during digestion and assimilation) gives an idea of their relative importance in the diet; in other words" you are what you eat"(DeNiro and Epstein 1978). Two food sources can be partitioned using the isotopie ratio for a single element (eg, 813C), or three food sources can be partitioned using isotopie ratios for two elements (eg, 513C and d15?)(Kwak and Zedler 1997). A number of recent papers have used geometric procedures to quantify the contributions of three food sources to the diet using 5I3C and d15?(Ben-David et al. 1997a, 1997b; Kline et al. 1993; Szepanski et al. 1999; Whitledge and Rabeni 1997). However, these methods do not provide correct solutions to this three-endmember mixing problem. The purpose of this paper is to point out the shortcomings of these methods and to propose an alternative procedure which avoids them. Figure 1 shows a graphical representation of the ana-lytical situation. The dietary isotopie composition is rep-resented by point D within the triangle bounded by the points for the adjusted food source isotopie compositions A', B\and C. In the geometric procedures, Euclidean distances are calculated for line segments DA', DB\and DC and are used to compute the dietary contributions. Several variations of this calculation have been utilized. Kline et al.(1993) used the following equation:?/? a-.?{DA!+ DB'+ DC)-OX\yt^??.