Department of Environmental Sciences Policy and Management, University of California Berkeley, Berkeley, California, USA.
Department of Biogeography, Faculty of Regional and Environmental Sciences, Trier University, Trier, Germany.
Mol Ecol. 2023 Dec;32(23):6489-6506. doi: 10.1111/mec.16873. Epub 2023 Feb 15.
The dynamic structure of ecological communities results from interactions among taxa that change with shifts in species composition in space and time. However, our ability to study the interplay of ecological and evolutionary processes on community assembly remains relatively unexplored due to the difficulty of measuring community structure over long temporal scales. Here, we made use of a geological chronosequence across the Hawaiian Islands, representing 50 years to 4.15 million years of ecosystem development, to sample 11 communities of arthropods and their associated plant taxa using semiquantitative DNA metabarcoding. We then examined how ecological communities changed with community age by calculating quantitative network statistics for bipartite networks of arthropod-plant associations. The average number of interactions per species (linkage density), ratio of plant to arthropod species (vulnerability) and uniformity of energy flow (interaction evenness) increased significantly in concert with community age. The index of specialization has a curvilinear relationship with community age. Our analyses suggest that younger communities are characterized by fewer but stronger interactions, while biotic associations become more even and diverse as communities mature. These shifts in structure became especially prominent on East Maui (~0.5 million years old) and older volcanos, after enough time had elapsed for adaptation and specialization to act on populations in situ. Such natural progression of specialization during community assembly is probably impeded by the rapid infiltration of non-native species, with special risk to younger or more recently disturbed communities that are composed of fewer specialized relationships.
生态群落的动态结构是由在空间和时间上发生物种组成变化的种间相互作用所导致的。然而，由于难以在长时间尺度上测量群落结构，我们研究生态和进化过程对群落组装相互作用的能力仍然相对未知。在这里，我们利用夏威夷群岛的地质年代序列，代表了 50 年到 415 万年的生态系统发展，使用半定量 DNA 宏条形码对 11 个节肢动物群落及其相关的植物分类群进行了采样。然后，我们通过计算节肢动物-植物关联二分网络的定量网络统计数据，研究了生态群落如何随群落年龄而变化。每个物种的平均相互作用数（连接密度）、植物与节肢动物物种的比例（脆弱性）和能量流动的均匀性（相互作用均匀性）随着群落年龄的增加而显著增加。专业化指数与群落年龄呈曲线关系。我们的分析表明，年轻的群落的特点是相互作用较少但更强，而随着群落的成熟，生物联系变得更加均匀和多样化。这种结构的转变在东毛伊岛（约 50 万年）和更古老的火山上尤为明显，在足够的时间过去后，适应和特化作用开始作用于原地的种群。在群落组装过程中，这种特化的自然进展可能会受到非本地物种的快速渗透的阻碍，对于由较少特化关系组成的较年轻或最近受到干扰的群落来说，风险特别大。
