A hallmark of living organisms is their capacity to modify the physical, chemical, and biological properties of ecosystems. Organisms exhibit heritable variation in the traits causing such modifications, meaning that phenotypic evolution by natural selection can drive ecosystem change. In adaptive radiations, for example, the traits under divergent selection are often the same as those used to exploit resources in the natural environment, making them good candidates for exploring feedbacks between phenotypic diversification and ecosystem dynamics. Using stickleback and whitefish as model organisms, we did a series of common gardening experiments to test whether contrasting fish phenotypes, arising from either genetic or environmentally induced differences between or within closely related species, have different effects on aquatic ecosystems.
Results/Conclusions
Our results show that phenotypic differences among organisms can cause considerable divergence not only to the ecological structure and function of communities (e.g. prey communities, primary production), but also to the physical and chemical characteristics of ecosystems (e.g. dissolved organic matter, and light transmission). We found that the size of ecosystem-effect contrasts resulting from phenotypic plasticity tended to be smaller than those resulting from different species, but this depended somewhat on the ecosystem metric and the treatment organism. We also found that the ecosystem divergence, caused by organisms with contrasting phenotypes, persisted beyond the time period when the organisms were present in the system. Overall, this suggests that phenotypic diversification of organisms can generate divergent ecosystem conditions, and this might modify the form and strength of natural selection so as to facilitate or constrain further phenotypic divergence.