Coexistence of helminth species in Lysapsus limellus (Anura: Pseudidae) from an Argentinean subtropical area: influence of biotic and abiotic factors

Abstract

Two types of pond were considered, one permanent and one semipermanent. The main goals of this study were: 1) to investigate the relationships between pond type, season, study time, frog body size and frog sex and the presence-absence and counts of helminth parasite species in the frog host, L. limellus, and 2) to examine the co-occurrence between the different parasite species in the frog host in terms of the structure, assembly and dynamics of the helminth infracommunity. Presences and absences of parasites were analyzed using logistic regression and counts of parasites were analyzed using log-linear modeling. To examine the association between parasite species, a principal components analysis was carried out on the correlation matrix for the counts. The pattern of co-occurrences was also examined through a randomization test. The main results obtained were: 1) five parasite species were in the infracommunity; 2) the pond type and the host size class were the principal factors related to the presence and absence of parasites for the three dominant species, while the year of study and the host sex were only important for one of the species; 3) for the counts of parasites, there were many more significant factors than there were for the analysis of presence and absence, with body size class and pond type always important factors for the three core species of the infracommunity, and the season, year of study and sex also sometimes important; and 4) strong associations were observed between some helminth species of the host from the permanent pond, but the same species did not co-occur in frogs in the semipermanent pond. The life histories of the five species can be considered as opportunistic or “r strategists”.