Traits define how organisms interact with their surrounding environment and with other organisms. Thus, trait composition of biological communities is expected to change predictably along environmental gradients. Because organisms’ traits, but not taxonomic identity, determine their fitness, trait-environment relationships should provide a better way to elucidate how biodiversity respond to environmental change. Here, we used data on tropical streams embedded in a landscape of intensive agriculture to investigate trait-environment and taxon-environment relationships in a set of 91 mayfly communities from southeastern Brazil. We expected that trait-environment relationships would be stronger than taxon-environment relationships and that the linkage between traits and environmental variables would provide mechanistic insights on environmental filtering. We found that variation in both species composition and traits were correlated to salinity, highlighting the influence of water salinization on mayfly communities due to agricultural practices. Surprisingly, using analogous statistical methods, in general, we found that the strengths of trait-environment relationships were lower than that of taxon-environment relationships. Further, (1) species responses to gradients were not correlated to similarity in their traits and (2) some species with different trait composition responded similarly to environmental variation, indicating that different suite of traits can cope with similar environmental contexts. Besides some cautionary results about trait-based approaches, results from taxon-based approaches indicated that variation in composition was more related to spatial variables, suggesting that dispersal limitation undermine its use for large scale assessments. Our results suggest that both taxon- and trait-based approaches have weakness and strengths and deciding between them for biomonitoring purposes will depend on spatial scales, trait interrelationships, and analytical methods.

性状定义了生物如何与其周围环境以及其他生物相互作用。因此，预计生物群落的特征组成会随着环境梯度发生可预测的变化。因为生物的特征而不是生物分类的身份决定了它们的适应性，所以特征与环境的关系应该提供一种更好的方法来阐明生物多样性如何对环境变化做出反应。在这里，我们使用了集约化农业景观中嵌入的热带溪流的数据，调查了巴西东南部91个may蝇群落中的性状-环境和分类-环境关系。我们期望特征与环境的关系比分类单元与环境的关系更强，并且特征与环境变量之间的联系将为环境过滤提供机械的见解。我们发现物种组成和性状的变化都与盐度相关，这突出了由于农业实践水盐碱化对may蝇群落的影响。出乎意料的是，通常使用类似的统计方法，我们发现特质-环境关系的强度低于分类群-环境关系的强度。此外，（1）物种对梯度的反应与其性状的相似性无关，（2）一些具有不同性状组成的物种对环境变化的反应相似，表明不同的特征可以应对相似的环境。除了有关基于特征的方法的一些警告性结果之外，基于分类单元的方法的结果表明，成分变化与空间变量更相关，这表明分散限制会破坏其在大规模评估中的使用。我们的研究结果表明，基于分类法和基于特征的方法都具有弱点和优势，出于生物监控的目的而在它们之间做出决定将取决于空间尺度，特征相互关系和分析方法。这表明散布限制会破坏其在大规模评估中的使用。我们的研究结果表明，基于分类法和基于特征的方法都具有弱点和优势，出于生物监控的目的而在它们之间做出决定将取决于空间尺度，特征相互关系和分析方法。这表明散布限制会破坏其在大规模评估中的使用。我们的研究结果表明，基于分类法和基于特征的方法都具有弱点和优势，出于生物监控的目的而在它们之间做出决定将取决于空间尺度，特征相互关系和分析方法。