Ecology. 2014 Jan;95(1):14-21. doi: 10.1890/13-0196.1.
Assessing trait responses to environmental gradients requires the simultaneous analysis of the information contained in three tables: L (species distribution across samples), R (environmental characteristics of samples), and Q (species traits). Among the available methods, the so-called fourth-corner and RLQ methods are two appealing alternatives that provide a direct way to test and estimate trait-nvironment relationships. Both methods are based on the analysis of the fourth-corner matrix, which crosses traits and environmental variables weighted by species abundances. However, they differ greatly in their outputs: RLQ is a multivariate technique that provides ordination scores to summarize the joint structure among the three tables, whereas the fourth-corner method mainly tests for individual trait-environment relationships (i.e., one trait and one environmental variable at a time). Here, we illustrate how the complementarity between these two methods can be exploited to promote new ecological knowledge and to improve the study of trait-environment relationships. After a short description of each method, we apply them to real ecological data to present their different outputs and provide hints about the gain resulting from their combined use.
L（物种在样本中的分布）、R（样本的环境特征）和 Q（物种性状）。在可用的方法中，所谓的第四角落和 RLQ 方法是两种有吸引力的替代方法，它们提供了一种直接测试和估计性状-环境关系的方法。这两种方法都是基于对第四角落矩阵的分析，该矩阵通过物种丰度加权交叉性状和环境变量。然而，它们在输出结果上有很大的不同：RLQ 是一种多元技术，提供了排序分数来总结三个表格之间的联合结构，而第四角落方法主要用于测试单个性状-环境关系（即一次一个性状和一个环境变量）。在这里，我们说明如何利用这两种方法的互补性来促进新的生态知识，并改善性状-环境关系的研究。在简要描述每种方法之后，我们将其应用于真实的生态数据，以展示它们不同的输出，并提供有关它们联合使用带来的收益的提示。
