Shifts from non-obligate generalists to obligate specialists in simulations of mutualistic network assembly

Understanding ecosystem recovery after perturbation is crucial for ecosystem conservation. Mutualisms contribute key functions for plants such as pollination and seed dispersal. We modelled the assembly of mutualistic networks based on trait matching between plants and their animal partners that have different degrees of specialization on plant traits. Additionally, we addressed the role of non-obligate animal mutualists, including facultative mutualists or non-resident species that have their main resources outside the target site. Our computer simulations show that non-obligate animals facilitate network assembly during the early stages, furthering colonization by an increase in niche space and reduced competition. While non-obligate and generalist animals provide most of the fitness benefits to plants in the early stages of the assembly, obligate and specialist animals dominate at the end of the assembly. Our results thus demonstrate the combined occurrence of shifts from diet, trait, and habitat generalists to more specialised animals.

Methods
Data was generated with computer simulations. The methods are described in the main text and the source code is provided here and described in the README.md file. The data produced with the simulations have been processed using Python scripts, which are also provided here and explained in the README.md file.

解析扰动后生态系统的恢复机制，对生态系统保护具有重要意义。互利共生关系可为植物提供授粉、种子传播等核心生态功能。我们基于植物与动物伙伴间的性状匹配（trait matching）构建了互利共生网络（mutualistic networks）的组装模型，这些动物伙伴对植物性状的特化程度各不相同。此外，我们还探讨了非专性动物互利共生者（non-obligate animal mutualists）的作用，这类共生者包括兼性互利共生者（facultative mutualists），以及主要资源位于研究样地之外的非定居物种。

本研究通过计算机模拟发现，非专性动物可在互利共生网络组装的早期阶段发挥促进作用：通过扩大生态位空间、降低种间竞争，促进物种定植。在网络组装早期，非专性与广食性动物可为植物提供绝大多数适合度收益；而到组装后期，专性（obligate）与特化动物则占据主导地位。因此，本研究结果证实，动物类群会同时发生从食性、性状与生境广适者向特化类群的转变。

方法
研究数据通过计算机模拟生成。实验方法详见正文，源代码已随本数据集一并提供，并在README.md文件中进行了说明。模拟生成的数据已通过Python脚本进行处理，相关脚本亦随本数据集提供，具体说明详见README.md文件。