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Volume 94, Issue 10 p. 2321-2333
Article

Phylogenetic trait-based analyses of ecological networks

Nicole E. Rafferty

Nicole E. Rafferty

Department of Zoology, University of Wisconsin, Madison, Wisconsin 53706 USA

Present address: Department of Ecology and Evolutionary Biology and Center for Insect Science, University of Arizona, Tucson, Arizona 85721 USA.

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Anthony R. Ives

Anthony R. Ives

Department of Zoology, University of Wisconsin, Madison, Wisconsin 53706 USA

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First published: 01 October 2013
Citations: 61
E-mail: [email protected]

Corresponding Editor: J. Cavendar-Bares.

Abstract

Ecological networks of two interacting guilds of species, such as flowering plants and pollinators, are common in nature, and studying their structure can yield insights into their resilience to environmental disturbances. Here we develop analytical methods for exploring the strengths of interactions within bipartite networks consisting of two guilds of phylogenetically related species. We then apply these methods to investigate the resilience of a plant–pollinator community to anticipated climate change. The methods allow the statistical assessment of, for example, whether closely related pollinators are more likely to visit plants with similar relative frequencies, and whether closely related pollinators tend to visit closely related plants. The methods can also incorporate trait information, allowing us to identify which plant traits are likely responsible for attracting different pollinators. These questions are important for our study of 14 prairie plants and their 22 insect pollinators. Over the last 70 years, six of the plants have advanced their flowering, while eight have not. When we experimentally forced earlier flowering times, five of the six advanced-flowering species experienced higher pollinator visitation rates, whereas only one of the eight other species had more visits; this network thus appears resilient to climate change, because those species with advanced flowering have ample pollinators earlier in the season. Using the methods developed here, we show that advanced-flowering plants did not have a distinct pollinator community from the other eight species. Furthermore, pollinator phylogeny did not explain pollinator community composition; closely related pollinators were not more likely to visit the same plant species. However, differences among pollinator communities visiting different plants were explained by plant height, floral color, and symmetry. As a result, closely related plants attracted similar numbers of pollinators. By parsing out characteristics that explain why plants share pollinators, we can identify plant species that likely share a common fate in a changing climate.