Influence of plant–pollinator interactions on the assembly of plant and hummingbird communities

Abstract

Summary Understanding how ecological processes structure species assemblages is a central issue in community ecology. While the influence of plant–pollinator interactions on each other's evolution is well recognized, their role in the assembly of interdependent communities of plants and pollinators is still unclear. Using data from seven communities of hummingbirds and plants that they pollinate from two tropical rain forest types (lowland and montane), we evaluated phylogenetic relationships and signal of functional traits, over space and time, to test predictions on the main processes (environmental filtering, facilitation or competition) that are driving these hummingbird–plant assemblages. Our findings suggest that the main processes driving these assemblages varied between hummingbirds and plants and between habitats, and even among communities at the same habitat. The non‐conserved floral trait and the phylogenetic patterns (even or random) give support to the hypothesis of facilitation or competition as processes regulating the composition of plant assemblages. Moreover, the positive relationship between fitness and flowering synchrony suggests facilitation as the most important mechanism for montane plant communities. Distinctively, for lowland plant communities, the combination of non‐conserved traits and clustered phylogenetic patterns may be a result of either adaptive radiation or biotic filtering driven by a particular pollinator species that plays a main role as plant community organizer. Lastly, evidence of trait conservatism, together with clustered or even phylogenetic patterns, suggests that facilitation or competition may drive the assembly of montane hummingbird communities, despite the predominance of random phylogenetic patterns. Synthesis. Overall, we present a pathway to identify central ecological processes that may drive the assembly of plant–pollinator communities. We show that different processes related with pollination that vary in space and time may contribute to the assembly of the interdependent tropical communities of plants and pollinators. These findings highlight the importance of considering ecological interactions when evaluating community assembly processes.

Pollination outcomes reveal negative density‐dependence coupled with interspecific facilitation among plants

“…Hummingbird‐pollinated plants experienced facilitation and competition in similar proportions. Previous studies suggested an interplay of facilitation and competition on hummingbird‐pollinated plant communities (Wolowski et al ; Bergamo et al ), and our results confirm that both interaction signs are similarly important for these plants.…”

The potential indirect effects among plants via shared hummingbird pollinators are structured by phenotypic similarity

“…This may be because tropical hummingbird‐pollinated plant communities studied here encompass distantly related plant lineages for which floral traits are not phylogenetically conserved (Wolowski et al. ). Overall, our findings give strength to the hypothesis that convergent evolution plays a major role in shaping floral traits and plant‐hummingbird interactions in the tropics (Martín González et al.…”

“…Flowering phenology data were collected monthly in all communities (ITA: Wolowski et al. , SVG: Vizentin‐Bugoni et al. , FAR and FAZ: Maruyama et al.…”

“…Flowering phenology data were collected monthly in all communities (ITA: Wolowski et al 2016, SVG: Vizentin-Bugoni et al 2016, FAR and FAZ: Maruyama et al 2015. All hummingbird-pollinated plant species in bloom were recorded monthly along pre-existing trails for at least 12 months of study.…”

Elevation predicts the functional composition of alpine plant communities based on vegetative traits, but not based on floral traits

“…Less well studied are floral traits that are important for the plants' sexual reproduction, which requires animal pollen vectors in zoophilous plants and was suggested to be of particular importance for alpine plant species (Fabbro and Körner 2004). The few studies that considered floral traits in a community-ecological context (e.g., Benadi et al 2014;Junker et al 2013;Runquist et al 2016;Wolowski et al 2017) suggest a contribution of these traits to plant community composition (Benadi 2015;Pauw 2013;Sargent and Ackerly 2007). Indeed, recent studies show that floral traits, such as morphology, colour, and scent shape plant-pollinator interactions, affect the diversity of flower visiting animals in communities, and explain the presence or absence of competition between plant species for pollinators (Carvalheiro et al 2014;Junker et al 2013Junker et al , 2015Junker and Parachnowitsch 2015;Kuppler et al 2016;Larue et al 2016).…”