Host body size and the diversity of tick assemblages on Neotropical vertebrates.
Identifying the factors that influence the species diversity and distribution of ticks (Acari: Ixodida) across vertebrate host taxa is of fundamental ecological and medical importance. Host body size is considered one of the most important determinants of tick abundance, with larger hosts having higher tick burdens. The species diversity of tick assemblages should also be greater on larger-bodied host species, but empirical studies testing this hypothesis are lacking. Here, we evaluate this relationship using a comparative dataset of feeding associations from Panama between 45 tick species and 171 host species that range in body size by three orders of magnitude. We found that tick species diversity increased with host body size for adult ticks but not for immature ticks. We also found that closely related host species tended to have similar tick species diversity, but correcting for host phylogeny did not alter the relationships between host body size and tick species diversity. The distribution of tick species was highly aggregated, with approximately 20% of the host species harboring 80% of all tick species, following the Pareto principle or 20/80 Rule. Thus, the aggregated pattern commonly observed for tick burdens and disease transmission also holds for patterns of tick species richness. Our finding that the adult ticks in this system preferentially parasitize large-bodied host species suggests that the ongoing anthropogenic loss of large-bodied vertebrates is likely to result in host-tick coextinction events, even when immature stages feed opportunistically. As parasites play critical roles in ecological and evolutionary processes, such losses may profoundly affect ecosystem functioning and services.
Department of Environmental Sciences, Wageningen University & Research, PO Box 47, 6700 AA Wageningen, The Netherlands; Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panamá, Panama.
Helen J
HJ
Esser
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA.
Janet E
JE
Foley
Department of Environmental Sciences, Wageningen University & Research, PO Box 47, 6700 AA Wageningen, The Netherlands.
Frans
F
Bongers
Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panamá, Panama.
Edward Allen
EA
Herre
Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panamá, Panama; Sam Noble Oklahoma Museum of Natural History and Department of Biology, University of Oklahoma, Norman, OK 73072-7029, USA.
Matthew J
MJ
Miller
Department of Environmental Sciences, Wageningen University & Research, PO Box 47, 6700 AA Wageningen, The Netherlands.
Herbert H T
HH
Prins
Department of Environmental Sciences, Wageningen University & Research, PO Box 47, 6700 AA Wageningen, The Netherlands; Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panamá, Panama.
Patrick A
PA
Jansen
20/80 Rule; Panama; Parasite fauna; Pareto principle; Proportional similarity; Species richness