A general hypothesis-testing framework for stable isotope ratios in ecological studies

作者：Turner Thomas F^*; Collyer Michael L; Krabbenhoft Trevor J

来源：Ecology, 2010, 91(8): 2227-2233.

DOI：10.1890/09-1454.1

• delta C-13
• delta N-15
• food web
• functional groups
• niche
• residual permutation
• stable isotopes

We propose a framework for hypothesis-testing of stable isotope ratios in ecological studies. Statistical procedures are based on analysis of nested linear models and a residual permutation procedure (RPP) that is employed to evaluate probabilities associated with test statistics. We used simulated examples and a real data set to illustrate the utility and generality of the method. First, we developed a test for differences in centroid location and dispersion of delta C-13 and delta N-15 values within and among groups of isotopic data. Second, we evaluated magnitude and direction of change in centroid position (termed "path'') of a pair of isotopic samples separated in space/time relative to paths of other paired sample sets. Third, we compared attributes of path trajectories (size, direction, and shape) over sample sets containing more than two samples to provide a quantitative description of how patterns of isotopic ratios change in response to spatial and temporal gradients. Examples are limited to the bivariate case (delta C-13-delta N-15 biplots), but the statistical method can readily be applied to univariate and multivariate cases.

• 出版日期2010-8