Abundance drives broad patterns of generalisation in plant–hummingbird pollination networks

Benno I Simmons,Ana M Martín González,Licléia C Rodrigues,Carlos Lara,Jesper Sonne,Márcia A Rocca,Peter A Cotton,Carsten Rahbek,Lynn V Dicks,Bo Dalsgaard,William J Sutherland,Liliana Rosero‐Lasprilla,Marlies Sazima,Jeferson Vizentin‐Bugoni,Boris A Tinoco,Oscar Humberto Marín–Gómez ,Marcelo Ferreira De Vasconcelos ,Pietro Kiyoshi Maruyama ,Raúl Ortiz‐Pulido ,María Alejandra Maglianesi

doi:10.1111/oik.06104

Abstract

Abundant pollinators are often more generalised than rare pollinators. This could be because abundant species have more chance encounters with potential interaction partners. On the other hand, generalised species could have a competitive advantage over specialists, leading to higher abundance. Determining the direction of the abundance–generalisation relationship is therefore a ‘chicken‐and‐egg’ dilemma. Here we determine the direction of the relationship between abundance and generalisation in plant–hummingbird pollination networks across the Americas. We find evidence that hummingbird pollinators are generalised because they are abundant, and little evidence that hummingbirds are abundant because they are generalised. Additionally, most patterns of species‐level abundance and generalisation were well explained by a null model that assumed interaction neutrality (interaction probabilities defined by species relative abundances). These results suggest that neutral processes play a key role in driving broad patterns of generalisation in animal pollinators across large spatial scales.

Highlights

Material and methodsPollination and other mutualistic associations are crucial for the functioning and maintenance of ecological communities (Heithaus 1974, Rech et al 2016, Ollerton 2017, Ratto et al 2018)
Abundant species are more likely to encounter a greater number of potential interaction partners than rare species (Vázquez et al 2007, 2009, Poisot et al 2015)
The wider diet breadth of generalist individuals could allow them to receive a more stable benefit over time in communities with high levels of variability or species turnover; generalisation increases the likelihood that a given mutualist will interact with the most beneficial partner; and generalists benefit from having diverse partners that occupy different niches but provide the same rewards via different mechanisms (Waser et al 1996, Albrecht et al 2012, CaraDonna et al 2017, Batstone et al 2018)

Summary

Introduction

Material and methodsPollination and other mutualistic associations are crucial for the functioning and maintenance of ecological communities (Heithaus 1974, Rech et al 2016, Ollerton 2017, Ratto et al 2018). We evaluate the direction of the abundance–generalisation relationship in plant–hummingbird pollination networks and use a null model to assess the extent to which observed patterns of species-level generalisation can be explained by neutral effects.

Results

Conclusion