Data from: Phylogenetic signal in module composition and species connectivity in compartmentalized host-parasite networks

Across different taxa, networks of mutualistic or antagonistic interactions show consistent architecture. Most networks are modular, with modules being distinct species subsets connected mainly with each other and having few connections to other modules. We investigate the phylogenetic relatedness of species within modules and whether a phylogenetic signal is detectable in the within- and among module connectivity of species using 27 mammal-flea networks from the Palaearctic. In the 24 networks that were modular, closely-related hosts co-occurred in the same module more often than expected by chance; in contrast, this was rarely the case for parasites. The within- and among-module connectivity of the same host or parasite species varied geographically. However, among-module but not within-module connectivity of host and parasites was somewhat phylogenetically constrained. These findings suggest that the establishment of host-parasite networks results from the interplay between phylogenetic influences acting mostly on hosts and local factors acting on parasites, to create an asymmetrically constrained pattern of geographic variation in modular structure. Modularity in host-parasite networks seems to result from the shared evolutionary history of hosts and by trait convergence among unrelated parasites. This suggests profound differences between hosts and parasites in the establishment and functioning of bipartite antagonistic networks.

跨不同生物类群，互利或拮抗交互网络均呈现出一致的拓扑结构。绝大多数网络均呈模块化特征：模块为相对独立的物种子集，内部个体间连接紧密，与其他模块的交互连接则相对稀缺。本研究依托古北界地区的27组哺乳动物-跳蚤交互网络，探究模块内部物种的系统发育亲缘关系，以及物种在模块内与模块间的连接模式是否存在系统发育信号。在其中24个呈模块化结构的网络中，亲缘关系较近的宿主物种在同一模块中共存的概率显著高于随机预期；与之形成鲜明对比的是，寄生物种几乎未呈现出这一规律。同一宿主或寄生物种的模块内与模块间连接模式均存在地理异质性。但仅宿主与寄生物的模块间连接模式存在一定程度的系统发育约束，模块内连接模式则无此特征。本研究结果表明，宿主-寄生物交互网络的形成，是主要作用于宿主的系统发育影响与主要作用于寄生物的本地环境因子相互作用的结果，最终造就了模块化结构地理变异的非对称约束模式。宿主-寄生物交互网络的模块化结构，似乎源于宿主的共同演化历史，以及非亲缘寄生物之间的性状趋同现象。这一结论揭示了宿主与寄生物在二部拮抗交互网络的构建与运行机制中存在的根本性差异。