Abstract Detail

Ecological Section

Bell, John M. [2], Karron, Jeffrey D. [2], Mitchell, Randall J. [1].

Interspecific competition for pollinator service lowers seed set and outcrossing rates in Mimulus ringens.

Sympatric plant species with similar flowering phenologies and floral morphologies may compete for pollinator service, and as a consequence may potentially influence each other’s reproductive success and mating system.Mimulus ringens and Lobelia siphilitica co-occur in wetland habitats of central and eastern North America. Both species produce blue zygomorphic flowers and share several species of bumble bee pollinators.To examine the effect of competition for pollinator service on seeds per fruit and outcrossing rates, we planted four experimental arrays of M. ringens, each consisting of genets with unique combinations of homozygous marker genotypes.In two arrays mixtures of M. ringens and L. siphilitica were planted in a checkerboard design.In the other two arrays only M. ringens individuals were present.Bumble bee pollinators frequently moved between Mimulus and Lobelia flowers in the mixed-species arrays, and 12% of the pollinator movements were interspecific transitions.Both the number of seeds per M. ringens fruit and the rate of outcrossing were significantly lower in the mixed-species arrays than in the Mimulus-only arrays.This is the first study to demonstrate that competition for pollinator service may directly influence a plant’s mating system.

1 - University of Akron, Biology Department, Akron, Ohio, 443225-3908, USA
2 - University of Wisconsin-Milwaukee, Department of Biological Sciences, P.O. Box 413, Milwaukee, Wisconsin, 53201, USA

Keywords:
competition for pollinator service
outcrossing rates
mating systems
Mimulus ringens.

Presentation Type: Paper
Session: 17-1
Location: Wasatch (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 1:15 PM
Abstract ID:6