Functional consequences of plant‐animal interactions along the mutualism‐antagonism gradient

Abstract

Abstract. Plant-animal interactions are pivotal for ecosystem functioning, and usually form complex networks involving multiple species of mutualists as well as antagonists. The costs and benefits of these interactions show a strong context-dependency directly related to individual variation in partner identity and differential strength. Yet understanding the context-dependency and functional consequences of mutualistic and antagonistic interactions on individuals remains a lasting challenge. We use a network approach to characterize the individual, plant-based pollination interaction networks of the Canarian Isoplexis canariensis (Plantaginaceae) with a mixed assemblage of vertebrate mutualists (birds and lizards) and invertebrate antagonists (florivores, nectar larcenists, and predispersal seed predators). We identify and quantify interaction typologies based on the sign (mutualistic vs. antagonistic) and strength (weak vs. strong) of animal-mediated pollination and test the relationship with individual female reproductive success (FRS). In addition, we document pollinator movement patterns among individual plants to infer events of pollen transfer/receipt that define the plant mating networks and test the relationship with FRS. We identify six interaction typologies along a mutualism-antagonism gradient, with two typologies being over-represented involving both mutualists and antagonists and influencing FRS. Plants showing strong mutualistic interactions, but also (weak or strong) interactions with antagonists are relatively better connected in the mating network (i.e., with higher potential to transfer or receive pollen). Thus, mixed flower visitor assemblages with mutualists and antagonists give plants increased their importance in the mating networks, promote outcrossing and increasing both female and male fitness. Our approach helps characterize plant-animal interaction typologies, the context-specificity of diversified mutualisms, and a better forecasting of their functional consequences.

Interaction motifs variability in a Mediterranean palm under environmental disturbances: the mutualism–antagonism continuum

“…Similar to previous findings by Rodríguez-Rodríguez et al (2017) for plant-pollinator interactions, we found that the best predictor correlated with dwarf palm dispersal effectiveness (a proxy for realized early recruitment) was the predefined interaction typologies. The mixed interaction modes of individual palms with frugivore assemblages combining both mutualists and antagonists had a stronger effect on seed dispersal effectiveness than plant traits or locality.…”

“…To identify the interaction typology, we followed the methodology proposed by Rodríguez-Rodríguez et al (2017). Based on the estimated interaction strengths, we characterized a quantitative version of the three-wise interaction typologies: each plant node (P) linked to a mutualistic (M) and/or an antagonistic (A) animal node, with the link values representing the summed interaction strengths of the individual palm with its M and A partner species (Fig.…”

Motifs in bipartite ecological networks: uncovering indirect interactions

“…While methods to enumerate weighted motifs are being developed (Bramon Mora et al 2018), there are a number of tractable methods to incorporate quantitative information in motif analyses. For example, interactions within motifs can be classified as 'strong' or 'weak' depending on whether a given interaction's strength is greater or lesser, respectively, than the median strength (Rodríguez-Rodríguez et al 2017). Alternatively, a suite of qualitative networks can be assembled by sampling a quantitative network in proportion to the strength of each interaction (Baker et al 2015).…”

Uncovering indirect interactions in bipartite ecological networks

“…In another example, motifs were used to disentangle the functional consequences of mutualism and antagonism in plant-animal interactions (Rodríguez-Rodríguez et al 2017). The authors created an interaction typology of three-species motifs based on the type (mutualistic or antagonistic) and strength (weak or strong) of species interactions with Isoplexis canariensis in North-West Tenerife.…”