Figures and data
Main analyses: effect of defensive symbionts on the fitness of hosts that are under attack of natural enemies. (a) overall model, (b) model including host family as moderator, (c) model including symbiont type (i.e., if the symbiont naturally infects the host species or if it was artificially introduced) as moderator, and (d) model including fitness measure as moderator. Positive values indicate a positive effect on the fitness of hosts. Therefore, positive values indicate higher fecundity, survival, and number of individuals that were uninfected by their natural enemies (i.e., uninfected hosts - number of individuals that were unsuccessfully parasitized or infected by their natural enemies). Negative values indicate that symbionts have a negative effect on fitness. Points are the weighted mean effect sizes ± 95% confidence intervals. Numbers above points are the number of effect sizes.
Results of the meta-analysis of the costs and benefits of carrying a symbiont and test of moderators for overall, host family, symbiont type, and fitness measure.
Test of heterogeneity (total, between studies and within studies) for each of the 17 meta-analytical models included in the main analyses.
Main analyses: effect of defensive symbionts on the fitness of hosts that are in the absence of natural enemies. (a) overall model, (b) model including host family as moderator, (c) model including symbiont type (i.e., if the symbiont naturally infects the host species or if it was artificially introduced) as moderator, and (d) model including fitness measure as moderator. Positive values indicate a positive effect on the fitness of hosts. Therefore, positive values indicate higher fecundity, survival, body size and decreased development time. Negative values indicate that symbionts have a negative effect on fitness. Points are the weighted mean effect sizes ± 95% confidence intervals. Numbers above points are the number of effect sizes.
Main analyses: effect of defensive symbionts on the fitness of natural enemies attacking hosts that are infected with symbionts. (a) overall model, (b) model including host family as moderator, (c) model including symbiont type (i.e., if the symbiont naturally infects the host species or if it was artificially introduced) as moderator, and (d) model including fitness measure as moderator (i.e., natural enemies’ body size, survival and load). Positive values indicate a positive effect on the fitness of hosts. Therefore, positive values indicate higher body size, survival, and natural enemy load (the amount of natural enemy replicating inside the host such as viruses and bacteria). Negative values indicate that symbionts have a negative effect on fitness. Points are the weighted mean effect sizes ± 95% confidence intervals. Numbers above points are the number of effect sizes.
