Data from: Parasite metacommunities: evaluating the roles of host community composition and environmental gradients in structuring symbiont communities within amphibians

1. Ecologists increasingly report the structures of metacommunities for free-living species, yet far less is known about the composition of symbiont communities through space and time. Understanding the drivers of symbiont community patterns has implications ranging from emerging infectious disease to managing host microbiomes.
2. Using symbiont communities from amphibian hosts sampled from wetlands of California, USA, we quantified the effects of spatial, habitat filtering, and host community components on symbiont occupancy and overall metacommunity structure.
3. We built upon a statistical method to describe metacommunity structure that accounts for imperfect detection in survey data – detection error-corrected elements of metacommunity structure (DECEMS) – by adding an analysis to identify covariates of community turnover. We applied our model to a metacommunity of 8 parasite taxa observed in 3571 Pacific chorus frogs (Pseudacris regilla) surveyed from 174 wetlands over 5 years.
4. Symbiont metacommunity structure varied across years, showing nested structure in three years and random structure in two years. Species turnover was most consistently influenced by spatial and host community components. Occupancy generally increased in more southeastern wetlands, and snail (intermediate-host) community composition had strong effects on most symbiont taxa.
5. We have used sophisticated but accessible statistical methods to reveal that spatial components - which influence colonization - and host community composition - which mediates transmission - both drive symbiont community composition in this system. These methods allow us to associate broad patterns of community turnover to local, species-level effects, ultimately improving our understanding of spatial community dynamics.

1. 生态学家日益报道自由生活物种的元群落（metacommunity）结构，但关于共生体（symbiont）群落在空间与时间维度上的组成，学界认知仍极为匮乏。解析共生体群落格局的驱动因子，其研究意义覆盖从新发传染病防控到宿主微生物组管理等诸多领域。
2. 本研究以采自美国加利福尼亚州湿地的两栖动物宿主共生体群落为研究对象，量化了空间因子、生境过滤以及宿主群落组分对共生体占用率及整体元群落结构的影响。
3. 本研究在可校正调查数据中检测不完善（imperfect detection）的元群落结构统计描述方法——检测误差校正元群落结构组分（detection error-corrected elements of metacommunity structure, DECEMS）——的基础上，新增了用于识别群落周转协变量的分析模块。我们将改进后的模型应用于一项历时5年的调查数据集：该数据集覆盖174处湿地，共调查了3571只太平洋树蛙（*Pseudacris regilla*），记录到8类寄生类群的共生体群落。
4. 共生体元群落结构随年份呈现动态变化：3个年份呈现嵌套结构，剩余2个年份则表现为随机结构。物种周转最稳定地受到空间因子与宿主群落组分的调控。共生体占用率总体上在东南部湿地中更高，而螺类（中间宿主）群落组成对多数共生类群均具有显著影响。
5. 本研究借助精密且易于推广的统计方法，揭示了本系统中两类驱动共生体群落组成的核心因子：一是影响定植过程的空间因子，二是介导传播过程的宿主群落组成。该方法可将群落周转的宏观格局与局域尺度的物种水平效应相关联，最终深化我们对空间群落动态的认知。