Fig1_code from Vector-borne parasite invasion in communities across space and time

While vector-borne parasite transmission often operates via generalist-feeding vectors facilitating cross-species transmission in host communities, theory describing the relationship between host species diversity and parasite invasion in these systems is underdeveloped. Host community composition and abundance vary across space and time, generating opportunities for parasite invasion. To explore how host community variation can modify parasite invasion potential, we develop a model for vector-borne parasite transmission dynamics that includes a host community of arbitrary richness and species' abundance. To compare invasion potential across communities, we calculate the community basic reproductive ratio of the parasite. We compare communities comprising a set of host species to their subsets, which allows for flexible scenario building including the introduction of novel host species and species loss. We allow vector abundance to scale with, or be independent of, community size, capturing regulation by feeding opportunities and non-host effects such as limited oviposition sites. Motivated by equivocal data relating host species competency to abundance, we characterize plausible host communities via phenomenological relationships between host species abundance and competency. We identify an underappreciated mechanism whereby changes to communities simultaneously alter average competency and the vector to host ratio and demonstrate that the interaction can profoundly influence invasion potential.

尽管媒介传播寄生虫的传播通常借助泛食性媒介完成，可促成宿主群落内的跨物种传播，但目前描述此类系统中宿主物种多样性与寄生虫入侵间关系的理论仍有待完善。宿主群落组成与种群丰度随时空动态变化，为寄生虫入侵创造了条件。为探究宿主群落变异如何改变寄生虫入侵潜力，我们构建了一款媒介传播寄生虫传播动力学模型，该模型涵盖任意物种丰富度的宿主群落及各物种种群丰度。为对比不同群落间的入侵潜力，我们计算了寄生虫的群落基本再生数（community basic reproductive ratio）。我们将包含完整宿主物种集合的群落与其子集进行比对，该方法可支持灵活构建多种情景，包括引入新型宿主物种以及发生物种丧失的场景。我们允许媒介丰度随群落规模发生比例变化，或与群落规模完全无关，以此刻画由取食机会驱动的种群调控效应，以及产卵位点受限等非宿主效应。鉴于宿主物种胜任力（host competency）与丰度间的关联数据存在歧义，我们通过宿主物种种群丰度与胜任力之间的现象学关系来表征合理的宿主群落。我们发现了一种此前未被充分重视的机制：群落变化可同时改变平均胜任力与媒介-宿主比，并证明二者的相互作用可对入侵潜力产生深远影响。