New insights into plants co‐existence in species‐rich communities: The pollination interaction perspective

Abstract

Questions: In animal-mediated pollination, pollinators can be regarded as a limiting resource for which entomophilous plant species might interact to assure pollination, an event pivotal for their reproduction and population maintenance. At community level, spatially aggregated co-flowering species can thus be expected to exhibit suitable suites of traits to avoid competition and ensure pollination. We explored the problem by answering the following questions: (i) are co-flowering species specialized on different guilds of pollinators? (ii) do co-flowering pollinator-sharing species segregate spatially? (iii) do co-flowering pollinator-sharing species that diverge in anther position spatially aggregate more than those that converge in anther position? Study site: Euganean Hills (NE Italy).Methods: Plant composition, flowering phenology and interactions between each entomophilous plant species and pollinating insects were monitored every fifteen days in 40 permanent plots placed in an area of 16 ha. We quantified the degree of flowering synchrony, pollinator-sharing and spatial aggregation between each pair of entomophilous species. We then tested the relationship between the degree of co-flowering, pollinator-sharing and spatial aggregation, and between spatial aggregation and anther position.Results: Entomophilous species converged, at least partially in flowering time, and the phenological synchronization of flowering was significantly associated with the sharing of pollinator guilds. Coflowering pollinator-sharing species segregated spatially. Furthermore, co-flowering pollinatorsharing species that diverged in anther position aggregated more than those that converged in anther position. Conclusions:Reproductive traits that facilitate the coexistence of co-flowering species include specialization on different pollinator guilds and a phenological displacement of the flowering time.Furthermore, in circumstances of increased competition due to phenological synchronization, pollinator sharing and spatial aggregation, the chance of an effective pollination might depend on differences in anther position, resulting in a divergent pollen placement on pollinators' body. One of the most interesting results we obtained is that the presence of one mechanism does not preclude the operation of others and each plant species can simultaneously exhibit different strategies. Although Accepted ArticleThis article is protected by copyright. All rights reserved. more studies are needed, our results can provide additional information about plant-plant interactions and add new insights into mechanisms allowing the coexistence of a high number of plant species into local communities.

How does urbanization affect the reproductive characteristics and ecological affinities of street plant communities?

“…Desaegher et al (2018) showed that floral visitors of insect families that had a preference for nontubular corollas (generally insects with small mouthparts and considered as specialists) were rare in urbanized areas of the Île-de-France region (see also Geslin, Gauzens, Thébault, & Dajoz, 2013). In different contexts, two recent community-level studies (Bergamo, Wolowski, Maruyama, Vizentin-Bugoni, & Sazima, 2018;Fantinato, Del Vecchio, Giovanetti, Acosta, & Buffa, 2018) suggested complex interplay of facilitation and competition processes among flowering plants through pollination by insects. In different contexts, two recent community-level studies (Bergamo, Wolowski, Maruyama, Vizentin-Bugoni, & Sazima, 2018;Fantinato, Del Vecchio, Giovanetti, Acosta, & Buffa, 2018) suggested complex interplay of facilitation and competition processes among flowering plants through pollination by insects.…”

“…In different contexts, two recent community-level studies (Bergamo, Wolowski, Maruyama, Vizentin-Bugoni, & Sazima, 2018;Fantinato, Del Vecchio, Giovanetti, Acosta, & Buffa, 2018) suggested complex interplay of facilitation and competition processes among flowering plants through pollination by insects. This differentiation may allow different pollen placement on pollinator bodies, which can reduce competition among plant species and increase effective pollination (Bergamo et al, 2018;Fantinato et al, 2018). These studies also showed that coflowering, pollinator-sharing species tended to differ in another position in the corollas.…”

“…This is consistent with the results of Deguines, Julliard, Flores, and Fontaine (2016), who showed that urbanization was associated with a shift in community composition of flower visitors toward generalist insects in France. In different contexts, two recent community-level studies (Bergamo, Wolowski, Maruyama, Vizentin-Bugoni, & Sazima, 2018;Fantinato, Del Vecchio, Giovanetti, Acosta, & Buffa, 2018) suggested complex interplay of facilitation and competition processes among flowering plants through pollination by insects. Both studies showed that, in a given area, plant species sharing the same pollinator guild tended to flower together (phenological synchronization), which can be interpreted as a pollinator-mediated facilitation by increasing pollinator attraction in dense flowering patches (Sargent & Ackerly, 2008).…”

“…These studies also showed that coflowering, pollinator-sharing species tended to differ in another position in the corollas. This differentiation may allow different pollen placement on pollinator bodies, which can reduce competition among plant species and increase effective pollination (Bergamo et al, 2018;Fantinato et al, 2018). The different mechanisms by which competition for pollinators can reduce plant fitness include low frequency of pollinator visits and heterospecific pollen deposition on stigmas, and were described in detail by Waser (1978).…”

Pollination and dispersal trait spectra recover faster than the growth form spectrum during spontaneous succession in sandy old‐fields

“…At the regional scale, reproductive processes involving pollination and seed dispersal are crucial because the production of seeds is necessary for the colonization of new sites (Escaravage & Wagner, ). Furthermore, in some plant communities, they also contribute to shaping patterns of species co‐occurrence at smaller scales (Fantinato, Del Vecchio, Giovanetti, Acosta, & Buffa, ; Heystek & Pauw, ). Processes linked to vegetative reproduction and growth in plant communities influence species co‐occurrence at a small spatial scale through interactions as competition for light, space and below‐ground resources (Kelemen et al., ; van der Maarel & Sykes, ).…”