Explaining the ecological causes of evolutionary diversification is a major focus of biology, but surprisingly little has been said about the effects of evolutionary diversification on ecosystems. The number of species in an ecosystem and their traits are key predictors of many ecosystem-level processes, such as rates of productivity, biomass sequestration, and decomposition. Using a mesocosm experiment, we tested for short-term ecosystem-level effects of adaptive radiation in threespine stickleback (Gasterosteus aculeatus) over the last 10,000 years. These fish have undergone recent parallel diversification in several lakes in coastal British Columbia, resulting in the formation of two specialized species (benthic and limnetic) from a generalist ancestor.
Results/Conclusions

We demonstrate that this diversification has strong effects on ecosystems, affecting prey community structure, total primary production, and the nature of dissolved organic materials that regulate the spectral properties of light transmission in the system. However, these ecosystem effects do not simply increase in their relative strength with increasing specialization and species richness; instead, they reflect the complex and indirect consequences of ecosystem engineering by sticklebacks. It is well known that ecological factors influence adaptive radiation. This study demonstrates that adaptive radiation, even over short time scales, can have profound effects on ecosystems.