Exploring the real cost of parasites: A meta-analysis of experimental studies

Knowledge of host-parasite interaction is important to the ecology and conservation of wild populations, yet determining the real impact of parasites on their free-ranging hosts has proven elusive. Captive and theoretical studies have quantified costs and identified life-history trade-offs, but integrating these parameters with field studies has proven elusive. Previous qualitative reviews of the costs of parasites to wild hosts have identified that there may be population costs as well as individual costs to wild hosts (Møller, 1997; Tompkins and Begon, 1999; Irvine, 2006). To date, no quantitative review of the cost of parasites has occurred. In an attempt to gain a better understanding of the cost of parasites, a meta-analysis was conducted on 42 datasets where effects of parasites on free-living hosts were determined by manipulating parasite load on the host.