The Effect of Nectar Variance on Bumblebee Patterns of Movement and Potential Gene Dispersal

Abstract

Ott, J. R., Real, L. A. and Silverfine, B. M. 1985. The effect of nectar variance on bumblebee patterns of movement and potential gene dispersal. - Oikos 45: 333-340. The effect of variation in nectar reward on flight patterns, and correlatively potential gene flow, was studied using an enclosed colony of Bombus pennsylvanicus foraging on an artificial flower system. At low nectar variance foragers primarily visited adjacent (near neighbor) plants. Foragers responded to increasing variation in nectar reward by deviating from near neighbor visitation. Correspondingly, significant increases in the mean and variance of interplant flight distance were observed. By applying the isolation-by-distance model of population structure and equating interplant flight distance variance with gene dispersal variance, neighborhood size, area and diameter were estimated. Neighborhood size and area increased approximately threefold and neighborhood diameter increased 65% over the range of nectar variances tested. These results suggest that variation in nectar reward encountered by foraging bumblebees could play a role in mediating pollen dispersal in natural systems.