Coevolution of foraging in bombus and nectar dispensing in chilopsis: a last dreg theory.

Flowers of Chilopsis linearis dispense nectar into pools and grooves. The bumblebee, Bombus sonorus, extracts pool nectar at a rate seven times faster than groove nectar. The result is the coevolution of a plant-pollinator system in which bees, while foraging efficiently, increase the number of flowers visited per calorie of nectar reward provided by the plant.