This chapter explores how the mathematical frameworks, empirical methods, and predictions introduced for community structure can be extended to ecosystem function. Also outlined is an alternative conceptual framework (biological stoichiometry) for evaluating eco-evolutionary dynamics at the ecosystem level. The key questions in this analysis include the importance of intraspecific diversity, the relative strength of the various effects, on what time scales do the effects play out, and to what extent are the effects direct or indirect. The chapter also addresses whether the effects of genotypes decrease toward higher levels of complexity (from phenotypes to communities to ecosystems), and to what extent feedbacks are evident-traits influence ecosystems which then influence traits.