Factors at multiple scales drive parasite community structure

Area of Science:

• Ecology
• Parasitology
• Community Ecology

Background:

• Ecological community assembly is a central question in ecosystem ecology.
• Communities are hierarchical, with factors operating at multiple scales influencing structure.
• Parasites offer a model system to study community assembly within hosts, which are part of larger communities.

Purpose of the Study:

• To investigate the relative importance of multi-scale drivers in parasite community assembly.
• To determine how patterns at one ecological scale can obscure patterns at another.
• To differentiate between passive sampling and ecological drivers in parasite distribution across scales.

Main Methods:

• Applied a Markov Random Fields model to analyze parasite infracommunities.
• Assessed beta-diversity and nestedness across 420 parasite assemblages in freshwater mussels.
• Compared results to simulations from four ecological null models across host species, sites, and time periods.

Main Results:

• Significant beta-diversity was observed between sites (25% variation) and host species (41%), exceeding expectations.
• Beta-diversity between individual hosts was lower than expected after accounting for host and parasite characteristics.
• Parasite communities exhibited less nestedness than expected when host/parasite factors were included, suggesting within-host modularity.

Conclusions:

• Multi-scale factors significantly influence parasite community assembly, with host species and site-level variation being key drivers.
• Within-host parasite interactions may create modularity, a pattern masked if higher-scale variations are not considered.
• An integrated approach considering multiple scales is crucial for understanding ecological community composition and avoiding misinterpretation of drivers.