High proportion of smaller ranged hummingbird species coincides with ecological specialization across the Americas
Jesper Sonne, Ana M. Martín González, Pietro K. Maruyama, Brody Sandel, Jeferson Vizentin-Bugoni, Matthias Schleuning, Stefan Abrahamczyk, Ruben Alarcón, Andréa C. Araujo, Francielle P. Araújo, Severino Mendes de Azevedo, Jr, Andrea C. Baquero, Peter A. Cotton, Tanja Toftemark Ingversen, Glauco Kohler, Carlos Lara, Flor Maria Guedes Las-Casas, Adriana O. Machado, Caio Graco Machado, María Alejandra Maglianesi, Alan Cerqueira Moura, David Nogués-Bravo, Genilda M. Oliveira, Paulo E. Oliveira, Juan Francisco Ornelas, Licléia da Cruz Rodrigues, Liliana Rosero-Lasprilla, Ana Maria Rui, Marlies Sazima, Allan Timmermann, Isabela Galarda Varassin, Zhiheng Wang, Stella Watts, Jon Fjeldså, Jens-Christian Svenning, Carsten Rahbek, and Bo Dalsgaard
Proc. R. Soc. B 283:20152512; doi:10.1098/rspb.2015.2512 (published February 3, 2016)
http://rspb.royalsocietypublishing.org/content/283/1824/20152512
Abstract
Ecological communities that experience stable climate conditions have been speculated to preserve more specialized interspecific associations and have higher proportions of smaller ranged species (SRS). Thus, areas with disproportionally large numbers of SRS are expected to coincide geographically with a high degree of community-level ecological specialization, but this suggestion remains poorly supported with empirical evidence. Here, we analysed data for hummingbird resource specialization, range size, contemporary climate, and Late Quaternary climate stability for 46 hummingbird–plant mutualistic networks distributed across the Americas, representing 130 hummingbird species (ca 40% of all hummingbird species). We demonstrate a positive relationship between the proportion of SRS of hummingbirds and community-level specialization, i.e. the division of the floral niche among coexisting hummingbird species. This relationship remained strong even when accounting for climate, furthermore, the effect of SRS on specialization was far stronger than the effect of specialization on SRS, suggesting that climate largely influences specialization through species' range-size dynamics. Irrespective of the exact mechanism involved, our results indicate that communities consisting of higher proportions of SRS may be vulnerable to disturbance not only because of their small geographical ranges, but also because of their high degree of specialization.
