Diverse communities typically consume more resources, which is generally attributed to resource-niche differences among species. However, this mechanism has been difficult to demonstrate. We simultaneously manipulated diversity and density among a community of aphid-predator consumers, within a response-surface design, and measured resulting effects on resource (prey) consumption.

Results/Conclusions

Any single consumer species rapidly plateaued in its ability to extract more resources with greater density, but this was not the case when multiple species were present. Indeed, 17-57% more of the prey resource was subject to attack by diverse communities than by the most voracious single species. Resource extraction by diverse communities was clearly super-additive at moderate consumer-resource ratios, whereas effects of single species were sub-additive across a wide range of densities. Thus, we found unambiguous evidence for an emergent increase in resource consumption with greater consumer diversity. This appeared to reflect relatively strong intraspecific, but weak interspecific, competition for resources.