Land use decouples parasite–metazoan host biodiversity associations in soils across subtropical and temperate zones in China

Abstract Aim Soils harbour a large number of unicellular eukaryotic parasites of metazoans, particularly Apicomplexa. Apicomplexan distribution, their associations with hosts, and impacts of human‐dominated land use are little studied. We aimed to fill this gap by a biodiversity survey across large spatial scales. Location China. Time period May to September 2021. Major taxa studied Soil Apicomplexa and Metazoa Methods We used metabarcoding to investigate the biogeography of and links between Apicomplexa and soil Metazoa in three human‐dominated ecosystem types (farmlands, residential areas and parks) and more natural forest ecosystems across subtropical, warm‐temperate and mid‐temperate climatic regions in China. Results Human‐dominated land use indirectly reduced apicomplexan taxon richness by reducing metazoan taxon richness. However, the richness reduction of parasites was generally more pronounced in subtropical and mid‐temperate regions than in the warm‐temperate region. Mechanisms driving the richness reduction of parasites also differed between climatic regions, with the reduction in the subtropical region less related to the decrease in metazoan richness than in the mid‐temperate region. Human‐dominated ecosystems reduced richness associations between parasites and Metazoa, and this disrupted the cascading effect of climatic factors from metazoan to parasite communities. Moreover, co‐occurrence analyses showed that metazoan taxa more abundant in human‐dominated land‐use systems with dryer and hotter conditions were less likely associated with apicomplexan taxa. Main conclusions We conclude that decreased host taxon richness is an important, but not the only driver of reduced parasite taxon richness in soil systems. Apicomplexan richness was largely decoupled from metazoan richness in human‐dominated ecosystems, which emphasizes the important role of human activities in rewiring fundamental ecological patterns with global change. Overall, the results advance our understanding of principle characteristics of and interactions in soil communities, and their response to human activities, especially agriculture and urbanization.