Aquatic Ecology Group, The David Attenborough Building, Department of Zoology, University of Cambridge, Cambridge, UK.
J Anim Ecol. 2021 May;90(5):1096-1108. doi: 10.1111/1365-2656.13436. Epub 2021 Feb 21.
Understanding how environmental drivers influence the assembly of parasite communities, in addition to how parasites may interact at an infracommunity level, are fundamental requirements for the study of parasite ecology. Knowledge of how parasite communities are assembled will help to predict the risk of parasitism for hosts, and model how parasite communities may change under variable conditions. However, studies frequently rely on presence-absence data and examine multiple host species or sites, metrics which may be too coarse to characterise nuanced within-host patterns. We utilised a novel host system, the freshwater mussel Anodonta anatina, to investigate the drivers of community structure and explore parasite interactions. In addition, we aimed to highlight consistencies and inconsistencies between PA and abundance data. Our analysis incorporated 14 parasite taxa and 720 replicate infracommunities. Using Redundancy Analysis, a joint species distribution model and a Markov random field approach, we modelled the impact of both host-level and environment-level characteristics on parasite structure, as well as parasite-parasite correlations after accounting for all other factors. This approach was repeated for both the presence and abundance of all parasites. We demonstrated that the regional species pool, individual host characteristics (mussel length and gravidity) and predicted parasite-parasite interactions are all important but to varying degrees across parasite species, suggesting that applying generalities to parasite community construction is too simplistic. Furthermore, we showed that PA data fail to capture important density-dependent effects of parasite load for parasites with high abundance, and in general performs poorly for high-intensity parasites. Host and parasite traits, as well as broader environmental factors, all contribute to parasite community structure, emphasising that an integrated approach is required to study community assembly. However, care must be taken with the data used to infer patterns, as presence-absence data may lead to incorrect ecological inference.
了解环境驱动因素如何影响寄生虫群落的组装，以及寄生虫在亚群落水平上如何相互作用，是寄生虫生态学研究的基本要求。了解寄生虫群落是如何组装的，将有助于预测宿主被寄生虫寄生的风险，并建立模型，预测在多变的环境条件下寄生虫群落可能发生的变化。然而，这些研究通常依赖于存在-缺失数据，并检查多个宿主物种或地点，这些指标可能过于粗糙，无法描述宿主内寄生虫的细微模式。我们利用一种新颖的宿主系统——淡水贻贝 Anodonta anatina，来研究群落结构的驱动因素，并探索寄生虫的相互作用。此外，我们旨在突出存在-缺失数据和丰度数据之间的一致性和差异。我们的分析纳入了 14 种寄生虫类群和 720 个重复的亚群落。我们使用冗余分析、联合物种分布模型和马尔可夫随机场方法，模拟了宿主水平和环境水平特征对寄生虫结构的影响，以及在考虑到所有其他因素后寄生虫之间的相互作用。我们对所有寄生虫的存在和丰度都重复了这种分析。我们表明，区域物种库、个体宿主特征（贻贝长度和育肥度）和预测的寄生虫-寄生虫相互作用都很重要，但在不同的寄生虫物种中程度不同，这表明将一般性原则应用于寄生虫群落构建过于简单化。此外，我们还表明，对于丰度较高的寄生虫，存在-缺失数据无法捕捉到寄生虫负荷的重要密度依赖性效应，而对于高强度寄生虫，其表现通常较差。宿主和寄生虫的特征，以及更广泛的环境因素，都有助于寄生虫群落结构的形成，这强调了需要采用综合方法来研究群落组装。然而，在推断模式时必须谨慎使用数据，因为存在-缺失数据可能导致错误的生态推断。
