Processes entangling interactions in communities: forbidden links are more important than abundance in a hummingbird–plant network

Abstract

Understanding the relative importance of multiple processes on structuring species interactions within communities is one of the major challenges in ecology. Here, we evaluated the relative importance of species abundance and forbidden links in structuring a hummingbird-plant interaction network from the Atlantic rainforest in Brazil. Our results show that models incorporating phenological overlapping and morphological matches were more accurate in predicting the observed interactions than models considering species abundance. This means that forbidden links, by imposing constraints on species interactions, play a greater role than species abundance in structuring the ecological network. We also show that using the frequency of interaction as a proxy for species abundance and network metrics to describe the detailed network structure might lead to biased conclusions regarding mechanisms generating network structure. Together, our findings suggest that species abundance can be a less important driver of species interactions in communities than previously thought.

Process-Based Species Pools Reveal the Hidden Signature of Biotic Interactions Amid the Influence of Temperature Filtering

“…In hummingbirds, the extreme metabolic demands of hovering flight lead to intense exploitative and interference competition for floral nectar resources (Feinsinger and Colwell 1978;Feinsinger et al 1979;Altshuler and Dudley 2002). In addition, hummingbirds partition resources through differences in beak morphology (Feinsinger and Colwell 1978;Maglianesi et al 2014;Vizentin-Bugoni et al 2014). However, the signature of niche differentiation might emerge only after accounting for the influence of environmental filters.…”

Hummingbird tongues are elastic micropumps

“…In addition it could also improve our understanding of broadscale ecological patterns (e.g. species range limits and competition in hummingbird assemblages [6], and phenological shifts with conservation implications [26]). …”

“…Therefore, the way in which they feed on nectar determines the peaks and span of their performance, and thus their behaviour (and evolutionary trajectory), across a range of environmental axes. Accordingly, the details of their feeding ecology and coevolution with flowers have been the subject of intense study for over 40 years [1][2][3][4][5][6]. Half a century's worth of coevolutionary theory, as understood through hummingbirds as an example, depends on obtaining an empirical and mechanistic understanding of the nectar collection process.…”

Heterospecific pollen deposition among plants sharing hummingbird pollinators in the Brazilian Atlantic Forest

“…The high amount of bromeliad pollen is a consequence of the high prevalence of this family as food source to hummingbirds in the Atlantic Forest (Buzato et al 2000;Machado & Semir 2006;Wolowski et al 2013;Vizentin-Bugoni et al 2014), contrasting with other biomes such as Cerrado or other tropical forests (Amaya-Márquez et al 2001;Borgella Jr. et al 2001;Lasprilla 2003;Araújo et al 2013). For instance, pollen of only two bromeliad species, among other 29 plant species, were found on the body of hummingbirds in Colombian Amazon (Lasprilla 2003).…”

“…Hummingbirds (Trochilidae) are important pollinators of a large array of Neotropical plants (Machado & Semir 2006;Rocca-de-Andrade 2006;Vizentin-Bugoni et al 2014), with highlight to the sub-family Phaethornithinae in the Brazilian Atlantic Forest (Sazima et al 1995(Sazima et al ,1996Buzato et al 2000;Wendt et al 2008). Among the Phaethornithinae, Ramphodon naevius is indicated as the main pollinating bird from the lowland Atlantic Forest (Sazima et al 1995;Buzato et al 2000;Wendt et al 2008).…”