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

Abstract

The nature and the strength of plant–frugivore interactions often vary along an antagonism–mutualism continuum and are highly influenced by the local ecological context (e.g. level of environmental disturbances). However, little is known concerning how the local ecological setting where plant–frugivore interactions take place affects the seed dispersal effectiveness (SDE) and, eventually, plant recruitment. This knowledge gap relates to the scarcity of empirical investigations on individual‐based plant–frugivore networks. We assessed whether the assembly of interaction modes (antagonist and mutualist) of the dwarf palm Chamaerops humilis (Arecaeae) affect the individual and the population level SDE in two Mediterranean sites differing in perturbation levels. We analysed the frequency distribution of interaction typologies and test its relationship with variation among individual palms in SDE. Additionally, we document how variation in interaction motif frequency (e.g. overrepresented interaction typologies) relates to changes in the SDE landscape of both disturbed study sites. We found that the interaction typologies of individual palms and its frugivores did not occur randomly. In a more complex landscape, interactions were more diverse and less dominated by simpler typologies, which may increase the stability of the plant–disperser interaction over the long term. We demonstrate that plants that interact with a more complex assemblage of frugivores, including both mutualistic and antagonistic partners, had the highest probability of recruitment. We found that the highly variable SDE among individual palms resulted from a few interaction modes occurring at higher than expected frequencies. We suggest this may be a reasonably frequent situation in diversified frugivore assemblages with a high heterogeneity of functional effects among mutualistic and antagonistic partners.

Interspecific interactions among functionally diverse frugivores and their outcomes for plant reproduction: A new approach based on camera-trap data and tailored null models

“…humilis ’ foraging by ungulate seed predators, enhancing thus seed survival and fruit removal by mutualistic animal associates ( Fig 7B ). Therefore, both, mutualistic and antagonistic partners that shape the interaction outcomes among individual plants lead to contrasting seed dispersal success [ 18 , 70 ], appearing to shape a complex web of direct and indirect effects which’s net effect is most likely dependent on the community context [ 52 ]. This outcome may be strongly dependent on initial population densities that would most likely alter the dynamics of the system, thus, the net effect of dispersal success, among other factors, will probably be a result of the abundance of different functional guild of frugivores (legitimate seed dispersers, pulp feeders and seed predators) [ 87 – 89 ].…”

“…badgers and foxes) are the most effective seed dispersers of C. humilis and P. bourgaeana [29,30], whereas wild ungulates can behave as seed predators or seed dispersers [29][30][31]. Therefore, a greater dispersal success of individuals bearing more fruits due to higher visitation of the most effective dispersers can be limited depending on whether ungulates behave mostly as dispersers or as seed predators [70]. Other environmental conditions derived from the micro (e.g.…”

The disruption of a keystone interaction erodes pollination and seed dispersal networks

“…2019 b ), consequently, networks with a greater number of different motifs would have a greater diversity of interactions (Jácome‐Flores et al. 2020). At the other level, a motif is composed of two or more positions that can be occupied by different species simultaneously (Appendix : Fig.…”

Hybrid networks reveal contrasting effects of agricultural intensification on antagonistic and mutualistic motifs

“…Also, Jácome‐Flores et al. (2020) reported that some interaction motifs were associated with seed dispersal effectiveness in individual‐based networks. Therefore, the network motif profile offers a network fingerprint that can be very useful to compare network properties, and study the impact of environmental perturbations on ecosystem functions.…”