Exploring non-invasive sampling of parasites by metabarcoding gastrointestinal nematodes in Madagascar frog species
Anuran parasites are poorly surveyed, despite arguably being one of the most important threats to Anuran populations worldwide. Additionally, parasites also interact with a number of other stressors, such as invasive species, pollution, sedimentation and changing light conditions, caused by anthropogenic disturbance in natural habitats. We aimed to explore the use of metabarcoding, a new, non-invasive tool to survey the parasite assemblages in frogs in different environments facing different levels of anthropogenic pressure. We collected fecal samples from frogs across three different transects in Ranomafana National Park, located in Southwestern Madagascar, and then used the 18S metabarcoding technique to identify nematode species from the collected fecal samples. We were able to find four different putative species, which were all identified to the genus level. Thus, the metabarcoding approach seems to provide similar diversity estimates and similar taxonomical accuracy as traditional methods. While the most degraded transect and the transect within protected area did not statistically differ from each other, the medium-impacted transect had both higher parasite prevalence and fecal egg counts than the other two. This result underlines that the relationship between habitat degradation and parasite dynamics is not linear, but is instead dependent on several factors. Our results further suggest that non-invasive sampling and metabarcoding can provide a suitable tool for intestinal parasite surveys in anuran host populations.