Estimating parasite diversity using non-parametric methods

Background/Question/Methods

Knowledge of parasite diversity is essential to answering various fundamental questions about host-parasite relationship from an ecological and evolutionary perspective.  However, current parasite databases at broad host taxonomic scales often face three major problems: records of parasite species are incomplete; host species are unevenly sampled; and different sampling strategies are applied in different reports. Therefore, true parasite species richness (PSR, the number of parasite species) need to be estimated from incomplete records using mathematical models. Many methods based on the observed species richness the relative abundance of the species can be borrowed from biodiversity studies of larger organisms. Using carnivore and their parasites as a model system, our study, for the first time, explores the application of some of the most popular mathematical methods in estimating true PSR in carnivore species. Records of parasites in free-ranging carnivore populations were compiled from published studies to comprise a large dataset as part of the Global Mammal Parasite Database. Parasites species are accumulated as the number of studies increased through years, and the overall observed PSR are compared with PSR estimated using mathematical models to assess the current status of current parasite records in wild carnivore species.

Results/Conclusions

Our results from multiple models consistently show that current records of parasites in wild carnivore species are incomplete and observed PSR is an underestimation of the true parasite diversity in carnivores. Because of the heterogeneity of sampling schemes in studies on wildlife infectious diseases, non-parametric methods can be extremely useful in estimating true PSR. Understanding true parasite diversity, in association with host and environmental factors can further provide valuable information for conservation of biodiversity including wildlife hosts and the parasites. Non-parametric methods have no requirement for parameters summarizing the sampling effort, and generally have relatively low data requirement. This is the first study to apply these methods in estimating wildlife parasite diversity at a broad spatial and taxonomic scale, and our results suggest a great need for further sampling of wildlife animals for their parasites, in company with advancing the modeling techniques for better estimating true diversity of parasites.