Abstract
BackgroundParasites significantly alter topological metrics describing food web structure, yet few studies have explored the relationship between food web topology and parasite diversity.Methods/Principal FindingsThis study uses quantitative metrics describing network structure to investigate the relationship between the topology of the host food web and parasite diversity. Food webs were constructed for four restored brackish marshes that vary in species diversity, time post restoration and levels of parasitism. Our results show that the topology of the food web in each brackish marsh is highly nested, with clusters of generalists forming a distinct modular structure. The most consistent predictors of parasite diversity within a host were: trophic generality, and eigenvector centrality. These metrics indicate that parasites preferentially colonise host species that are highly connected, and within modules of tightly interacting species in the food web network.Conclusions/SignificanceThese results suggest that highly connected free-living species within the food web may represent stable trophic relationships that allow for the persistence of complex parasite life cycles. Our data demonstrate that the structure of host food webs can have a significant effect on the establishment of parasites, and on the potential for evolution of complex parasite life cycles.
Highlights
Food webs are abstractions of nature that describe community topology via networks of trophic interactions [1,2]
Conclusions/Significance: These results suggest that highly connected free-living species within the food web may represent stable trophic relationships that allow for the persistence of complex parasite life cycles
The identity of the best-fit model is secondary to our data departing from a power-law distribution; this suggests that super-generalist species are more rare than would be expected if the networks were built using a scale-free distribution to describe the number of interactions per species
Summary
Food webs are abstractions of nature that describe community topology via networks of trophic interactions [1,2]. Several topology-based metrics have become key parameters in the theoretical search for general patterns in food webs [7], and as determinants of food web stability [9]. Parasites have largely been understudied in these systems, and there have been few attempts to use the topology of the free-living host community to describe parasite dynamics [10,11,12]. Patterns of parasite diversity are contingent upon, and susceptible to, the structure and distribution of feeding interactions and the abundance of host in the free-living community [23]. The structure of the host food web is likely to exert a strong selective pressure on the evolution of parasite transmission strategies and subsequent patterns of parasite diversity observed in extant systems [23,24,25]. Parasites significantly alter topological metrics describing food web structure, yet few studies have explored the relationship between food web topology and parasite diversity
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