Abstract Detail

Life after Arabidopsis thaliana: Using non-model organisms to understand species interactions

Carr , David E [1], LeCroy, Kathryn [2], Lee, De'Ashia [3], Link, Rosabeth I [4].

Using the Mimulus guttatus species complex to understand the mechanisms of pollinator attraction.

The Mimulus guttatus species complex provides an excellent system in which to study the effects of variation in plant phenotypes on plant-pollinator mutualisms.  In Mimulus guttatus, the primary reward for pollinators is pollen, a critical protein source for bees and their developing larvae.  Inbreeding in M. guttatus reduces pollen production and pollen viability, and we have previously demonstrated that this results in large differences in the protein available per flower.  Our previous work has also demonstrated that pollinators strongly discriminate against inbred plants and that this discrimination is independent of obvious visual cues.  In a series of experiments using live plants, artificial plants, and olfactometer experiments, we addressed the following questions: 1) Do bumble bees (Bombus impatiens) make foraging decisions based on the presence of pollen rewards?  2) Is bee preference for outbred plants due primarily to the lower quality rewards in inbred plants?  3) Do volatile cues mediate the interaction between M. guttatus and its bumble bee pollinators?
To isolate the effects of pollen rewards on preference, we provisioned artificial flowers with either fertile or sterile anthers taken fresh from live M. guttatus plants.  Free-flying bees significantly preferred artificial flowers provisioned with fertile anthers.  In an olfactometer experiment, one flower was provided with the scent of fertile anthers while another was provided with the scent of sterile anthers.  Again bees significantly preferred flowers provided with the cues of fertile anthers.  In our earlier experiments, pollen viability was confounded with inbreeding, but we developed populations of outbred plants with high frequenceies of male sterility.  When given the choice between these high sterility outbred populations, fully fertile outbred populations, and inbred populations, bees significantly discriminated against inbred plants relative to all outbred populations.  Visitation to the fertile and high sterility outbred populations was statistically indistinguishable.  Finally, in an olfactometer experiment that provided pairwise choices between the scent of inbred and outbred plants, bumble bees that had never foraged on M. guttatus showed a significant preference for outbred plants.  Although foraging bees show a strong preference for fertile anthers over sterile anthers and can choose fertile anthers by olfactory cues alone, they discriminate against inbred plants even when their fertility is superior to outbred plants.  This preference may be due to differences between inbred and outbred plants in volatile cues that are uncorrelated with information regarding the primary rewards in this species.

1 - University of Virginia, Blandy Experimental Farm, 400 Blandy Farm Lane, Boyce, VA, 22620, USA
2 - University of Pittsburgh, Department of Biological Sciences, 4249 Fifth Avenue, Pittsburgh, PA, 15260-3929, USA
3 - Howard University, Department of Biology, 415 College Street NW , Washington, DC, 20059, USA
4 - Dickinson College, Department of Biology, PO Box 1773, Carlisle, PA, 17013, USA

Keywords:
Bombus impatiens
bumble bee
floral reward
inbreeding
mating system
Mimulus guttatus
pollen
pollinator
volatile.

Presentation Type: Symposium or Colloquium Presentation
Session: SY10
Location: Pines North/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 2:15 PM
Number: SY10003
Abstract ID:488
Candidate for Awards:None