Skip to main content
Dryad logo

Data from: Do animals living in larger groups experience greater parasitism? A meta-analysis

Citation

Rifkin, Joanna L.; Nunn, Charles L.; Garamszegi, László Z. (2012), Data from: Do animals living in larger groups experience greater parasitism? A meta-analysis, Dryad, Dataset, https://doi.org/10.5061/dryad.v5007p45

Abstract

Parasitism is widely viewed as the primary cost of sociality and a constraint on group size, yet studies report varied associations between group size and parasitism. Using the largest database of its kind, we performed a meta-analysis of 69 studies of the relationship between group size and parasite risk, as measured by parasitism and immune defenses. We predicted a positive correlation between group size and parasitism with organisms that show contagious and environmental transmission, and a negative correlation for searching parasites, parasitoids, and possibly vector-borne parasites (based on the encounter-dilution effect). Overall, we found a positive effect of group size (r=0.187) that varied in magnitude across transmission modes and measures of parasite risk, with only weak indications of publication bias. Among different groups of hosts, we found a stronger relationship between group size and parasite risk in birds than in mammals, which may be driven by ecological and social factors. A meta-regression showed that effect sizes increased with maximum group size. Phylogenetic meta-analyses revealed no evidence for phylogenetic signal in the strength of the group size-parasitism relationship. We conclude that group size is a weak predictor of parasite risk except in species that live in large aggregations, such as colonial birds, where effect sizes are larger.

Usage Notes