Flowering overlap and floral trait similarity help explain the structure of pollination networks

Abstract

1. Co-flowering communities are usually characterized by high plant generalization but knowledge of the underlying factors leading to high levels of generalization and pollinator sharing, and how these may contribute to network structure is still limited.2. Flowering phenology and floral trait similarity are considered among the most important factors determining plant generalization and pollinator sharing.However, these have been evaluated independently even though they can act in concert with each other. Moreover, the importance of flowering phenology and floral similarity, via their effects on plant generalization, in the structure of plant-pollinator networks has been scarcely studied. Here, we aim to evaluate the effect of flowering phenology and floral similarity in mediating the degree of pollinator sharing and plant generalization in two coastal communities and uncover their importance as drivers of plant-pollinator network structure.3. We recorded flower production per species, as well as the identity and frequency of floral visitors along the entire flowering season. We estimated the degree of flowering overlap, the degree of floral similarity (using floral traits associated with size and colour) and the degree of pollinator sharing among plant species within both communities. 4. Structural equation models (SEM) showed a positive effect of flowering overlap on pollinator sharing and plant generalization. Pollinator sharing and plant generalization positively affected network nestedness. Furthermore, SEM showed a direct positive effect of flowering overlap on network modularity. The SEM analyses also revealed a significant interaction effect of floral similarity and flowering overlap on pollinator sharing, with consequences for network nestedness in one community. 5. Synthesis. Our results highlight the importance of integrating multiple axes of differentiation such as flowering phenology and floral similarity into our understanding of the drivers of plant-pollinator network structure.

Plant spatial aggregation modulates the interplay between plant competition and pollinator attraction with contrasting outcomes of plant fitness

“…To evaluate the effect of the spatial arrangement of modulating the opposing effects of plant-plant interaction and plant-pollinator interaction of plant reproductive success, we used Structural Equation Models (SEMs) (Suárez-Mariño et al ., 2022) with a multigroup analysis context. The multigroup context was used to further test the hypothesis that different processes affect plant reproductive success at different spatial scales.…”

Different influences of phylogenetically conserved and independent floral traits on plant functional specialization and pollination network structure

“…Thus, z value for each species can be considered as its modularity contribution in the network (Suaŕez-Mariño et al, 2022). Similar with the previous studies, weighted versions of z and c were calculated using species strength instead of species degree here (Watts et al, 2016).…”

“…This finding indicated other unmeasured traits such as phenological factors, to some degree, accounting for the nested structure of plant-pollinator network in the study community. For instance, Suaŕez-Mariño et al (2022) showed that an increase in flowering overlap led to a higher degree of plant generalization and, in turn, with consequences for network nestedness. Furthermore, pollinators may play a more active role in the definition of interaction identity than plants because of pollinator mobility (Bascompte and Jordano, 2007).…”

“…It thus demands a more holistic view to assess the effect of floral traits on network metrics. For example, Suaŕez-Mariño et al (2022) revealed floral similarity had a significant interaction effect on pollinator sharing with flowering overlap and an indirect influence of on network nestedness as a consequence. However, we cannot tell which traits are more important than others using the floral similarity method.…”

“…Floral traits are one of the most important determinants of network patterns by mediating interactions with floral visitors ( Junker et al., 2013 ; Watts et al., 2016 ; Lara-Romero et al., 2019 ; Lázaro et al., 2020 ; Suárez-Mariño et al., 2022 ). First, phenotypic complementarity or morphological match may determine to what degree plants and pollinators can interact with each other in the community and, thus, the realized connectance and species’ position in pollination network ( Rezende et al., 2007a ; Stang et al., 2007 ).…”