Abstract Understanding how ecological and evolutionary processes shape biodiversity across hierarchical levels is a central goal in ecology, and parasite communities provide a valuable model for investigating assembly rules because they are directly constrained by their hosts. In this study, we investigated how taxonomic (TD), functional (FD), and proxy phylogenetic diversity (PPD) of parasite communities vary across two congeneric fish hosts ( Hypostomus hermanni and H. regani ) collected from two rivers (Batalha River and Ivaí River). We quantified diversity at multiple organizational levels, including α-diversity within host individuals, β1 variation among host individuals within the same host species, β2 variation between host species, and γ-diversity across habitats. Parasite communities were more similar among host individuals sampled within the same river than between rivers. Alpha diversity differed primarily in TD and FD, with H. hermanni from the Batalha River showing the highest values, whereas αPPD showed limited variation among host species. Beta diversity analyses revealed weak departures from random expectations within host species (β1) but strong differentiation between host species (β2) across TD, FD, and PPD. Overall, our findings indicate that host species remains a central driver of parasite diversity, while highlighting that taxonomic, functional, and phylogenetic facets respond differently to host and habitat-related factors.
Lehun et al. (Tue,) studied this question.