Plants (Oct 2023)

Context-Dependent Ant-Pollinator Mutualism Impacts Fruit Set in a Hummingbird-Pollinated Plant

  • Priscila Bruno Cardoso,
  • Eduardo Soares Calixto,
  • Helena Maura Torezan-Silingardi,
  • Kleber Del-Claro

DOI
https://doi.org/10.3390/plants12213688
Journal volume & issue
Vol. 12, no. 21
p. 3688

Abstract

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Context-dependence in mutualisms is a fundamental aspect of ecological interactions. Within plant-ant mutualisms, particularly in terms of biotic protection and pollination, research has predominantly focused on elucidating the benefits while largely overlooking potential costs. This notable gap underscores the need for investigations into the drawbacks and trade-offs associated with such mutualistic relationships. Here, we evaluated the role of pericarpial nectaries (PNs) in shaping the dynamics of ant-pollinator mutualisms. Specifically, we investigated whether ants visiting the PN of Palicourea rigida (Rubiaceae) could deter hummingbirds and disrupt pollination, ultimately influencing fruit production. Our research involved manipulative experiments and observation of ant-pollinator interactions on P. rigida plants in the Brazilian savannah. We found that visiting ants can deter hummingbirds and/or disrupt pollination in P. rigida, directly influencing fruit set. However, these results are species-specific. The presence of very aggressive, large predatory ants, such as E. tuberculatum, had a negative impact on hummingbird behavior, whereas aggressive mid-sized ants, such as C. crassus, showed no effects. Our study illuminates the multifaceted aspects of ant-plant mutualisms and underscores the importance of evaluating costs and unexpected outcomes within these ecological relationships.

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