With support from the National Science Foundation, we conducted a series of single-bee-species removal experiments at the Rocky Mountain Biological Laboratory. Most theory on biodiversity-functioning relationships suggests that these relationships are saturating, such that removal of a single species is typically unlikely to affect functioning. In a series of replicated field experiments published in PNAS [link to paper], we removed six of the 11 bumble bee species in our system and showed that these removals consistently affect behavioral plastic responses of remaining bees in the system (in particular, their floral fidelity) which cascaded to functional effects on pollination, from pollen carriage and deposition, all the way through to reduced seed set in Delphinium barbeyi, whose flowers are visited by most of the bumble bees in this system. We are still analyzing results from this four-year field project.