An expanded species-area perspective on helminth diversity and infection load in lizards: A phylogenetic comparative approach.

Abstract

Hosts function as ecological islands for endoparasites, offering structured habitats that support parasite survival, growth, and reproduction. Larger and older hosts are often expected to harbour more diverse and abundant parasitic assemblages due to increased structural complexity and longer exposure times. In this study, we investigated how host body size and phylogenetic relatedness influence endoparasite mean richness and mean intensity of infection in lizards from the Atlantic Rainforest of northeastern Brazil. We analysed 121 parasitised specimens representing 15 species, recording body size metrics (SVL and mass) and calculating parasitological indices. Significant phylogenetic signal was detected for host body size (SVL and mass) and mean intensity of infection, whereas no phylogenetic signal was found for mean parasite richness. Contrary to the island theory predictions, PGLS models revealed a significant negative relationship between mean SVL/mass and mean intensity of infection. Furthermore, no significant relationship was found between host body size (SVL or mass) and mean parasite richness, regardless of the evolutionary model used. The pPCA identified a predominance of global structure (phylogenetic relatedness), explaining 42.15% of the variation, while local structures, reflecting niche differentiation, accounted for 18.61%. Our results demonstrate that lizard-parasite interactions are shaped by a complex synergy between conserved evolutionary templates and opportunistic ecological responses, highlighting the necessity of integrated phylogenetic approaches in parasitological studies.