Species Structure of Bumblebee Communities in North America and Europe

Abstract

The competitive exclusion principle states that two species cannot coexist on the same limiting resource. It is possible to view bumblebees Bombus spp. (and other pollinators) as a limiting resource which is partitioned by the flowering plants in a community. I have chosen the alternative view which considers flowering plants as a limiting resource that is partitioned by bumblebees. The fact that bumblebees are annual species, while many of the plants they visit are long-lived perennials, lends support to this interpretation. Furthermore, many plant species may have other means of effecting pollination in addition to bumblebees. Because the relationship between bumblebees and flowers is generally mutualistic, consideration of both views is likely to be most fruitful.