1995/12/01 by Isabelle M. Côté, I. M. Cote, Robert Poulin +1 · 3 citations
Agricultural and Biological Sciences · Environmental Science · #Animal Ecology and Behavior Studies #Rabbits: Nutrition, Reproduction, Health
paper · doi:10.1093/beheco/6.2.159
openalex publication_date 1995/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
The size of groups formed by social animals is thought to result from a combination of selection pressures acting on individuals to maximize their fitness. In addition to commonly-invoked selective agents (e.g., predation), a growing number of studies suggest that levels of parasitism may be related to host group size and that parasites may influence optimal group size. We used a meta-analysis to quantify die intraspecific association found in published studies between prevalence and intensity of parasitism and host group size in a variety of taxa. We considered separately contagious parasites, which are transmitted via contact with infected individuals or feces, and mobile parasites which do not need proximity among hosts for transmission. In addition to mode of transmission, host group mobility was examined as a potential correlate of die association. Consistent positive correlations were found between host group size and both the prevalence and intensity of contagious parasites. By contrast, the intensity of infection by mobile parasites consistendy decreased as host group size increased. Host group mobility had no apparent effect on either the strength or die direction of these correlations. Although few experimental studies examined the causal effect of parasitism on host group size, strong circumstantial evidence was provided, at least for mobile parasites, by many reports of larger host group sizes following increases in parasite abundance. Our results therefore suggest that parasites with different modes of transmission can exert conflicting selection on host group size. The trends found in the meta-analysis, however, do not hold in interspecific comparative studies, possibly owing to differences among related species in die relative importance of parasitism as a selective force.