Abstract
Robert MacArthur developed a theory of community assembly based on competition. By incorporating energy flow, MacArthur's theory allows for predictions of community function. A key prediction is that communities minimise energy wastage over time, but this minimisation is a trade‐off between two conflicting processes: exploiting food resources, and maintaining low metabolism and mortality. Despite its simplicity and elegance, MacArthur's principle has not been tested empirically despite having long fascinated theoreticians. We used a combination of field chronosequence experiments and laboratory assays to estimate how the energy wastage of a community changes during succession. We found that older successional stages wasted more energy in maintenance, but there was no clear pattern in how communities of different age exploited food resources. We identify several reasons for why MacArthur's original theory may need modification and new avenues to further explore community efficiency, an understudied component of ecosystem functioning.