title: Habitat assessment ability of bumble-bees implies frequency-dependent selection on floral rewards and display size.
abstract: Foraging pollinators could visit hundreds of flowers in succession on mass-flowering plants, yet they often visit only a small number--potentially saving the plant from much self-pollination among its own flowers (geitonogamy). This study tests the hypothesis that bumble-bee (Bombus impatiens) residence on a particular plant depends on an assessment of that plant's reward value relative to the overall quality experienced in the habitat. In a controlled environment, naive bees were given experience in a particular habitat (all plants having equal nectar quality or number of rewarding flowers), and we tested whether they learn about and adaptively exploit a new habitat type. Bees' residence on a plant (number of flowers probed per visit) was eventually invariant to a doubling of absolute nectar quality and increased only slightly with a doubling of absolute flower number in the habitat. These results help to explain why pollinators are quick to leave highly rewarding plants and suggest that the fitness of rewarding plant traits will often be frequency dependent. One implication is that geitonogamy may be a less significant constraint on the evolution of rewarding traits than generally supposed.
authors: Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada. jmbierna@zoo.utoronto.ca
authors: Jay M
authors: JM
authors: Biernaskie
authors: Robert J
authors: RJ
authors: Gegear
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology*; D017753:Ecosystem; D005247:Feeding Behavior / Q000502:physiology*; D035264:Flowers / Q000502:physiology*
references: Proc Natl Acad Sci U S A. 1995 Feb 28;92(5):1446-50
references: 11607514
references: Evolution. 2002 Jan;56(1):31-41
references: 11915852
references: Theor Popul Biol. 1976 Apr;9(2):129-36
references: 1273796
references: Philos Trans R Soc Lond B Biol Sci. 2003 Jun 29;358(1434):991-1004
references: 12831464
references: Heredity (Edinb). 2004 Mar;92(3):242-8
references: 14666135
references: Proc Biol Sci. 2005 Dec 22;272(1581):2651-7
references: 16321788
references: Trends Ecol Evol. 1993 Sep;8(9):321-5
references: 21236182
references: Oecologia. 1986 May;69(2):309-315
references: 28311376
references: Evolution. 1987 Sep;41(5):948-968
references: 28563419
references: Evolution. 1980 May;34(3):475-488
references: 28568699