title: Pollinator service only depends on nectar production rates in sparse populations.
abstract: As predicted, approach rate by bumblebees is strongly related to the nectar production rate of Echium vulgare plants in a sparse population, while in a dense population such a relationship is completely absent. These findings are confirmed by additional experiments with potted plants that were placed inside and outside a natural population. The results suggest that the direction of selection on nectar production may vary in space or time depending on population density. Such variation may help to explain the large genetic variation we found earlier for E. vulgare in our study area.
authors.affiliation: Section Plant Ecology, Institute for Evolutionary and Ecological Sciences, University of Leiden, PO Box 9516, 2300, RA Leiden, The Netherlands. Klinkhamer@RULSFB.LeidenUniv.nl
authors.forename: Peter G L
authors.initials: PG
authors.lastname: Klinkhamer
authors.forename: Peter-Paul
authors.initials: PP
authors.lastname: van der Lugt
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001516:Bees; D036661:Echium / Q000502:physiology*; D014644:Genetic Variation; D011058:Pollen; D011157:Population Dynamics; D012098:Reproduction