Host-parasite interaction networks between nematodes and non-volant small mammals in Brazil: A systematic review and ecological network analysis.

Rodents and didelphids are highly diverse and abundant groups that can be found in different ecological niches, including anthropized environments. This can favor a high diversity of zoonotic agents, constituting a complex network of ecological interactions. Nematode parasites can have adaptative flexibility to emerge as new diseases, considering its ecology and diversity, so we aimed to evaluate the functional role of a network interaction between small mammals and nematodes parasites. We used a literature search to construct our network. A total of 52 articles were selected for analysis, from which 80 records of nematodes parasitizing small mammals were retrieved, being 24 species associated with Didelphimorphia and 56 with Rodentia. No nematode species were found parasitizing hosts from both orders. The network exhibited significant modularity (QW = 0.62, P = 0.01), but did not show significant overall specialization (H2 = 0.48, P = 0.23), nor nestedness (WNODF metric = 0.03, P = 0.1), but there is a nestedness patterns both within modules (WNODASM = 0.17, P = 0.02) and across the entire network (WNODA = 0.03, P = 0.01). We observed 18 modules all related to the host family. All the hosts roles were classified as either ultraperipheral (81.58 %) or peripheral (18.42 %); and the nematodes were 90 % classified as ultraperipheral, 7.5 % classified as peripheral. Only Aspidodera raillieti and Guerrerostrongylus zetta were classified as provincial hubs. This could highlight the importance of niche sharing by hosts in the cycle transmission of those parasites and how the loss of these key species could result in module fragmentation and compromise system stability, emphasizing their critical role in network architecture and in hotspots of biodiversity and threaten biomes such as Atlantic Forest and Pantanal.