title: Asymmetric and frequency-dependent pollinator-mediated interactions may influence competitive displacement in two vernal pool plants.
abstract: A plant species immigrating into a community may experience a rarity disadvantage due to competition for the services of pollinators. These negative reproductive interactions have the potential to lead to competitive displacement or exclusion of a species from a site. In this study, we used one- and two-species arrays of potted plants to test for density and frequency dependence in pollinator-mediated and above-ground intraspecific and interspecific competition between two species of Limnanthes that have overlapping ranges, but rarely occur in close sympatry. There were asymmetric competitive effects; the species responded differently to their frequency within 16-plant replacement series arrays. Limnanthes douglasii rosea experienced stronger reductions in lifetime and per-flower fertility, likely due to pollinator-mediated competition with Limnanthes alba. This effect may be linked to asymmetrical competition through heterospecific pollen transfer. This study demonstrates that pollinator-mediated competition may discourage establishment of L. d. rosea in sites already occupied by its congener.
authors.affiliation: Department of Plant Biology, University of Minnesota, 250 Biological Sciences Center, 1445 Gortner Avenue, St. Paul, MN 55108, USA. rbriscoe@umn.edu
authors.forename: Ryan Briscoe
authors.initials: RB
authors.lastname: Runquist
authors.forename: Maureen L
authors.initials: ML
authors.lastname: Stanton
mesh_terms: D000818:Animals; D002140:California; D017753:Ecosystem; D035264:Flowers; D019684:Magnoliopsida / Q000502:physiology*; D054817:Pollination