Jiang Feng, Xun Yanhan, Cai Huiying, Jin Guangze
Center for Ecological Research Northeast Forestry University Harbin China.
Ecol Evol. 2017 Dec 20;8(2):1107-1116. doi: 10.1002/ece3.3691. eCollection 2018 Jan.
Although phylogenetic-based approaches have been frequently used to infer ecological processes, they have been increasingly criticized in recent years. To date, the factors that affect phylogenetic signals and further the ability of phylogenetic distance to predict trait dispersion have been assumed but not empirically tested. Therefore, we investigate which factors potentially influence the ability of phylogenetic distance to predict trait dispersion. We quantified the phylogenetic and trait dispersions across size classes and spatial scales in a 9-ha old-growth temperate forest dynamics plot in northeastern China. Phylogenetic signals at the community level were generally lower than those at the species pool level, and phylogenetically clustered communities showed lower phylogenetic signals than did overdispersed communities. This pattern might explain the other three findings of our study. First, phylogenetically overdispersed communities performed better at predicting trait dispersion than did clustered communities. Second, the mean pairwise distance (MPD)-based metric exhibited a stronger correlation with trait dispersion than did the mean nearest taxon distance (MNTD)-based metric. Finally, the MNTD-based metric showed that the prediction accuracy for trait dispersion decreased with increasing spatial scales, whereas its effects were weak on the MPD-based metric. In addition, phylogeny could not determine the dispersions of all functional axes but was able to predict certain traits depending on whether they were evolutionarily conserved. These results were conserved when we removed the effects of space and environment. Our findings highlighted that using phylogenetic distance as a proxy of trait similarity might work in a temperate forest depending on the species in local communities sampled from total pool as well as the traits measured. Utilizing these rules, we should rethink the conclusions of previous studies that were based on phylogenetic-based approaches.
尽管基于系统发育的方法经常被用于推断生态过程，但近年来它们受到了越来越多的批评。迄今为止，影响系统发育信号以及系统发育距离预测性状离散能力的因素一直是假设的，尚未经过实证检验。因此，我们研究了哪些因素可能影响系统发育距离预测性状离散的能力。我们在中国东北一个9公顷的老龄温带森林动态样地中，对不同大小等级和空间尺度上的系统发育和性状离散进行了量化。群落水平的系统发育信号通常低于物种库水平，系统发育聚类的群落比过度分散的群落显示出更低的系统发育信号。这种模式可能解释了我们研究的其他三个发现。第一，系统发育过度分散的群落比聚类群落更能准确预测性状离散。第二，基于平均成对距离（MPD）的指标与性状离散的相关性比基于平均最近分类单元距离（MNTD）的指标更强。最后，基于MNTD的指标表明，性状离散的预测准确性随着空间尺度的增加而降低，而其对基于MPD的指标的影响较弱。此外，系统发育不能决定所有功能轴的离散，但能够根据某些性状是否在进化上保守来预测它们。当我们去除空间和环境的影响时，这些结果仍然成立。我们的研究结果强调，将系统发育距离作为性状相似性的替代指标，在温带森林中可能有效，这取决于从总体库中采样的当地群落中的物种以及所测量的性状。利用这些规则，我们应该重新思考以前基于系统发育方法的研究结论。
