Laboratório de Fitoecologia e Fitogeografia, Departamento de Botânica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Plant Biol (Stuttg). 2013 Sep;15(5):858-67. doi: 10.1111/j.1438-8677.2012.00699.x. Epub 2012 Dec 17.
Understanding how species traits evolved over time is the central question to comprehend assembly rules that govern the phylogenetic structure of communities. The measurement of phylogenetic signal (PS) in ecologically relevant traits is a first step to understand phylogenetically structured community patterns. The different methods available to estimate PS make it difficult to choose which is most appropriate. Furthermore, alternative phylogenetic tree hypotheses, node resolution and clade age estimates might influence PS measurements. In this study, we evaluated to what extent these parameters affect different methods of PS analysis, and discuss advantages and disadvantages when selecting which method to use. We measured fruit/seed traits and flowering/fruiting phenology of endozoochoric species occurring in Southern Brazilian Araucaria forests and evaluated their PS using Mantel regressions, phylogenetic eigenvector regressions (PVR) and K statistic. Mantel regressions always gave less significant results compared to PVR and K statistic in all combinations of phylogenetic trees constructed. Moreover, a better phylogenetic resolution affected PS, independently of the method used to estimate it. Morphological seed traits tended to show higher PS than diaspores traits, while PS in flowering/fruiting phenology depended mostly on the method used to estimate it. This study demonstrates that different PS estimates are obtained depending on the chosen method and the phylogenetic tree resolution. This finding has implications for inferences on phylogenetic niche conservatism or ecological processes determining phylogenetic community structure.
了解物种特征随时间的演变过程是理解支配群落系统发育结构的组装规则的核心问题。在生态上相关特征中测量系统发育信号 (PS) 是理解系统发育结构社区模式的第一步。可用于估计 PS 的不同方法使得难以选择最合适的方法。此外，替代的系统发育树假设、节点分辨率和进化枝年龄估计可能会影响 PS 测量。在这项研究中，我们评估了这些参数在多大程度上影响 PS 分析的不同方法，并讨论了在选择使用哪种方法时的优缺点。我们测量了在巴西南部的Araucaria 森林中发生的内生动物物种的果实/种子特征和开花/结实物候，并使用 Mantel 回归、系统发育特征向量回归 (PVR) 和 K 统计量评估它们的 PS。在构建的所有系统发育树组合中，Mantel 回归与 PVR 和 K 统计量相比，结果总是不那么显著。此外，更好的系统发育分辨率会影响 PS，而与用于估计 PS 的方法无关。形态种子特征往往比分散体特征显示出更高的 PS，而开花/结实物候的 PS 主要取决于用于估计 PS 的方法。本研究表明，不同的 PS 估计值取决于所选方法和系统发育树分辨率。这一发现对推断系统发育生态位保守主义或决定系统发育群落结构的生态过程具有影响。
