Disentangling the role of floral sensory stimuli in pollination networks

Abstract

Despite progress in understanding pollination network structure, the functional roles of floral sensory stimuli (visual, olfactory) have never been addressed comprehensively in a community context, even though such traits are known to mediate plant–pollinator interactions. Here, we use a comprehensive dataset of floral traits and a novel dynamic data-pooling methodology to explore the impacts of floral sensory diversity on the structure of a pollination network in a Mediterranean scrubland. Our approach tracks transitions in the network behaviour of each plant species throughout its flowering period and, despite dynamism in visitor composition, reveals significant links to floral scent, and/or colour as perceived by pollinators. Having accounted for floral phenology, abundance and phylogeny, the persistent association between floral sensory traits and visitor guilds supports a deeper role for sensory bias and diffuse coevolution in structuring plant–pollinator networks. This knowledge of floral sensory diversity, by identifying the most influential phenotypes, could help prioritize efforts for plant–pollinator community restoration.

Floral volatiles structure plant–pollinator interactions in a diverse community across the growing season

“…Previous studies have illustrated the importance of floral VOCs in community‐level plant–pollinator interactions, mainly in Mediterranean systems with disparate groups of pollinator taxa (Kantsa et al, ; Kantsa et al, ). Here, in a mesic montane meadow, we show that floral volatiles contributed to the nested structure but not the modular structure of forb–bee interactions.…”

“…However, at a broader spatial or temporal scale that would encompass several pollination syndromes and greater phylogenetic diversity, we might expect a stronger signal of floral VOCs to the modules that these broad taxonomic pairings could create. For example, although Kantsa et al () did not explicitly evaluate network‐level metrics of plant–pollinator interaction structure (e.g. modularity or nestedness) with respect to floral VOCs, they found that one group of floral VOCs—sesquiterpenes—was related to the distribution of plant–pollinator interactions (i.e.…”

“…One factor that has received insufficient investigation as a contributor to network nestedness is the VOCs emitted by flowers. Pollinators are known to exhibit preferences for certain combinations, or ‘bouquets’, of volatile compounds (Dobson, ; Wright, Lutmerding, Dudareva, & Smith, ), and these preferences can correlate with patterns of visitation (Junker, Hocherl, & Bluthgen, ; Kantsa et al, ). We might expect generalist pollinators to be attracted, in part, to many forb species with a range of floral VOCs, and specialist pollinators to be attracted to fewer forb species that emit similar, specific suites of floral VOCs that are nested subsets of generalist bouquets.…”

Meta-networks for the study of biogeographical traits in ecological networks: the Mexican hummingbird-plant assemblage

“…Migratory hummingbirds have significantly higher c-values, that is, a relatively high proportion of their interactions are with plant species from other modules, increasing overall network cohesiveness (Olesen et al 2007;Tylianakis et al 2010;Stouffer and Bascompte 2011) and the potential importance of indirect interactions. In highly seasonal pollination networks this role is achieved by pollinator species with long phenophases, who connected species with much more restricted activity periods (Martín González et al 2012;Kantsa et al 2018). Modular networks are expected to be highly resilient, as disturbances are less likely to spread beyond modules (Olesen et al 2007;Tylianakis et al 2010;Stouffer and Bascompte 2011).…”

“…For instance, the study of interactions between plants and their pollinators over different seasons and years, including species whose phenophases may not fully overlap, has enabled us to explore the effect of climate, resource seasonality and species phenophases on community structure and species' roles. Besides a more accurate understanding of community structure and build up, these networks allow us to characterize more accurate the role of species and potential fluctuations over time (Martín González et al 2012;Chacoff et al 2017, Kantsa et al 2018. Similarly, the study of "meta-networks", i.e.…”