Are hummingbirds generalists or specialists? Using network analysis to explore the mechanisms influencing their interaction with nectar resources

PLoS One. 2019 Feb 27;14(2):e0211855. doi: 10.1371/journal.pone.0211855. eCollection 2019.

Abstract

Mutualistic interactions are powerful drivers of biodiversity on Earth that can be represented as complex interaction networks that vary in connection pattern and intensity. One of the most fascinating mutualisms is the interaction between hummingbirds and the plants they visit. We conducted an exhaustive search for articles, theses, reports, and personal communications with researchers (unpublished data) documenting hummingbird visits to flowers of nectar-rewarding plants. Based on information gathered from 4532 interactions between 292 hummingbird species and 1287 plant species, we built an interaction network between nine hummingbird clades and 100 plant families used by hummingbirds as nectar resources at a continental scale. We explored the network architecture, including phylogenetic, morphological, biogeographical, and distributional information. As expected, the network between hummingbirds and their nectar plants was heterogeneous and nested, but not modular. When we incorporated ecological and historical information in the network nodes, we found a generalization gradient in hummingbird morphology and interaction patterns. The hummingbird clades that most recently diversified in North America acted as generalist nodes and visited flowers with ornithophilous, intermediate and non-ornithophilous morphologies, connecting a high diversity of plant families. This pattern was favored by intermediate morphologies (bill, wing, and body size) and by the low niche conservatism in these clades compared to the oldest clades that diversified in South America. Our work is the first effort exploring the hummingbird-plant mutualistic network at a continental scale using hummingbird clades and plant families as nodes, offering an alternative approach to exploring the ecological and evolutionary factors that explain plant-animal interactions at a large scale.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Biodiversity
  • Birds / physiology*
  • Body Size
  • Feeding Behavior / physiology*
  • Flowers / physiology
  • Plant Nectar / physiology*
  • Plant Physiological Phenomena*
  • Pollination / physiology
  • Seasons
  • South America
  • Specialization
  • Symbiosis / genetics

Substances

  • Plant Nectar

Grants and funding

Financial support was provided by the project “Develop a matrix of interactions between hummingbird species and their nectar plants” funded by the US Forest Service International Program’s Western Hummingbird Partnership to MCA and CIR-F. CIR-F received a doctoral scholarship from the Consejo Nacional de Ciencia y Tecnología (CONACyT, No. 207196). Additional research funds were provided by research grants from Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica (PAPIIT, Ref. IN210908, Ref. IN216514, Ref. IN216617) and Posgrado en Ciencias Biológicas UNAM to MCA. The Department of Ecology and Evolutionary Biology of the University of Arizona, the James R. Silliman Memorial Research Grant, the Departamento de Biología Evolutiva, Instituto de Ecología, A.C. (Ref. 20030/10563), a NSF grant to the University of Arizona Research Training Group (RTG) in the Analysis of Biological Diversification, and a grant (Ref. 25922-N) and a doctoral scholarship (No. 56254) from the CONACyT to JFO provided partial funding during the early stages of this project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.