Asymmetric and frequency-dependent pollinator-mediated interactions may influence competitive displacement in two vernal pool plants

Authors

  • Ryan Briscoe Runquist,

    Corresponding author
    1. Department of Evolution and Ecology, Center for Population Biology, University of California Davis, Davis, CA, 95616, USA
    • Department of Plant Biology, University of Minnesota, St. Paul, MN, USA
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  • Maureen L. Stanton

    1. Department of Evolution and Ecology, Center for Population Biology, University of California Davis, Davis, CA, 95616, USA
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Correspondence: E-mail: rbriscoe@umn.edu

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.

Ancillary