Global patterns of interaction specialization in bird–flower networks

Abstract

Aim: Among the world's three major nectar-feeding bird taxa, hummingbirds are the most phenotypically specialized for nectarivory, followed by sunbirds, while the honeyeaters are the least phenotypically specialized taxa. We tested whether this phenotypic specialization gradient is also found in the interaction patterns with their floral resources.Location: Americas, Africa, Asia and Oceania/Australia. Methods:We compiled interaction networks between birds and floral resources for 79 hummingbird, nine sunbird and 33 honeyeater communities. Interaction specialization was quantified through connectance (C), complementary specialization (H 2 0 ), binary (Q B ) and weighted modularity (Q), with both observed and null-model corrected values. We compared interaction specialization among the three types of bird-flower communities, both independently and while controlling for potential confounding variables, such as plant species richness, asymmetry, latitude, insularity, topography, sampling methods and intensity.Results: Hummingbird-flower networks were more specialized than honeyeaterflower networks. Specifically, hummingbird-flower networks had a lower proportion of realized interactions (lower C), decreased niche overlap (greater H 2 0 ) and greater modularity (greater Q B ). However, we found no significant differences between hummingbird-and sunbird-flower networks, nor between sunbird-and honeyeaterflower networks.

Adaptive radiation and the evolution of nectarivory in a large songbird clade

“…Interestingly, our findings of rapid and extensive body size evolution among honeyeaters are in stark contrast to the two other major nectarivorous clades of birds—the hummingbirds and sunbirds—which exhibit comparatively limited body size diversity, but greater overall phenotypic specialization for interaction with their flower resources (Stiles ; Fleming and Muchhala ; Zanata et al. ). Fleming and Muchhala () attributed the among‐clade differences in nectarivory specialization and body size diversity to variation in floral resource predictability among major regions, ranging from highest in the Neotropics to comparatively low in Australia.…”

Defaunation as a trigger for the additional loss of plant species in fragmented landscapes: considerations on the state of Espírito Santo, southeastern Brazil

“…Mostly due to their small size, hummingbirds are poorly studied and the impact of their pollination on plant reproductive success is hard to estimate. However, the very strong coevolutionary patterns of the New World Hummingbirds (Cotton 1998;Zanata et al 2017) suggest that hummingbirds have been extremely important in the evolution and diversity of tropical plants. The state of Espírito Santo has about 33 species of hummingbirds that range in size from ~2-9 g, with short to long bills and that inhabit a variety of habitat types (Ruschi 1982;Ridgely et al 2015).…”

Long‐term effects of land‐use change on bird communities depend on spatial scale and land‐use type

“…As mobile organisms that can move freely between habitats with a diverse suite of body size, feeding, and behavioral traits, bird community structure and composition can quickly change in response to environmental perturbations on short-time scales (Thorn et al 2018). Birds also perform a wide range of important ecosystem processes including pollination (Zanata et al 2017), seed dispersal (Sekercioglu et al 2004), and can also be important topdown controls on lower trophic levels (Gruner 2004). Birds also perform a wide range of important ecosystem processes including pollination (Zanata et al 2017), seed dispersal (Sekercioglu et al 2004), and can also be important topdown controls on lower trophic levels (Gruner 2004).…”