Araújo Felipe D C, Santos Rubens M
Department of Biology, Graduate Program in Applied Botany, Federal University of Lavras, Lavras, MG, 37200-000, Brazil.
Department of Forestry, Federal University of Lavras, Lavras, MG, 37200-000, Brazil.
Oecologia. 2019 Mar;189(3):795-802. doi: 10.1007/s00442-019-04358-4. Epub 2019 Feb 23.
Environmental gradients play a key role in shaping diversity in tropical forests. However, we have a little understanding of how evolutionary diversity is affected by gradients and the role of niche persistence in flooded forests in dry biomes. Here, we assessed the evolutionary diversity across a flooding gradient in the Caatinga Domain of South America. We established 120 plots across four tributaries of the São Francisco River, eastern Brazil, consisting of 72 plots in flooded, 24 in occasionally flooded, and 24 in unflooded forests. We computed richness, phylogenetic diversity (PD), mean nearest taxon distance (MNTD), and mean pairwise phylogenetic distance (MPD) and their standardized effect sizes (ses.PD, ses.MNTD, and ses.MPD). We found low richness, low PD, and high MNTD values in flooded forests relative to unflooded and occasionally flooded forests. MPD did not differ across the flooding gradient. The standardized effect size metrics were higher in flooded forests. Despite the unflooded and occasionally flooded forests being rich in terms of species and correlated phylogenetic structure, flooded forests showed more lineage diversity than expected by chance. We assessed whether this pattern could be driven by resprouting ability testing its phylogenetic signal. Resprouting is randomly distributed across phylogeny, but plant communities are likely assembled from random draws of the resprouters' lineage pool. Quantifying evolutionary diversity across flooding gradients in dry environments brought new insights to how the same environmental filters may lead to disparate patterns of evolutionary diversity and the role of response traits in allowing certain clades to persist in flooded habitats.
环境梯度在塑造热带森林的多样性方面起着关键作用。然而，我们对进化多样性如何受到梯度影响以及生态位持久性在干旱生物群落中洪水泛滥森林中的作用了解甚少。在这里，我们评估了南美洲卡廷加地区沿洪水梯度的进化多样性。我们在巴西东部圣弗朗西斯科河的四条支流上建立了120个样地，其中72个样地位于洪水泛滥森林，24个位于偶尔被洪水淹没的森林，24个位于未被洪水淹没的森林。我们计算了丰富度、系统发育多样性（PD）、平均最近分类单元距离（MNTD）和平均成对系统发育距离（MPD）及其标准化效应大小（ses.PD、ses.MNTD和ses.MPD）。我们发现，与未被洪水淹没和偶尔被洪水淹没的森林相比，洪水泛滥森林的丰富度低、PD低且MNTD值高。MPD在整个洪水梯度上没有差异。洪水泛滥森林的标准化效应大小指标更高。尽管未被洪水淹没和偶尔被洪水淹没的森林在物种和相关系统发育结构方面很丰富，但洪水泛滥森林显示出比偶然预期更多的谱系多样性。我们通过测试其系统发育信号来评估这种模式是否可能由萌蘖能力驱动。萌蘖在系统发育中随机分布，但植物群落可能是从萌蘖者谱系库的随机抽取中组装而成的。量化干旱环境中洪水梯度上的进化多样性，为相同的环境筛选如何导致不同的进化多样性模式以及响应性状在允许某些进化枝在洪水泛滥栖息地中持续存在的作用带来了新的见解。
