Interactions between resource and consumer species are organized in ecological networks. Species interactions in these networks are influenced by the functional traits of the interacting partners, but the generality of trait-based interaction rules and the relationship between functional traits and a species’ specialization on specific interaction partners are not yet understood. Here we combine data on eight interaction networks between fleshy-fruited plants and frugivorous birds sampled across the tropical and subtropical Andean range. We test which combinations of morphological plant and animal traits determine trait matching between resource and consumer species in these networks. In addition, we test which of the morphological traits influence functional specialization of plant and bird species. In a meta-analysis across network-specific fourth-corner analyses, we found that plant–animal trait pairs related to size matching (fruit size–beak size) and avian foraging behavior (plant height–wing shape and crop mass–body mass) were positively related in these networks. The degree of functional specialization on specific interaction partners was positively related to crop mass in plants and to the pointedness of the wing in birds. Our findings show that morphological trait matching between fleshy-fruited plants and frugivorous birds is a general phenomenon in plant–frugivore networks across the Andes and that specific plant and bird traits can be used to approximate the degree of functional specialization. These insights into the generality of interaction rules are the base for predictions of species interactions in ecological networks, for instance in novel communities in the future, and can be applied to identify plant and animal species that fulfill specialized functional roles in ecological communities.
Bibliographical noteFunding Information:
Acknowledgements – We thank two anonymous reviewers for their constructive feedback on our manuscript. Furthermore, we are grateful to the members of the Laboratorio de Ecología de Aves – IER for their help in the field in Argentina. Funding – We gratefully acknowledge the support of the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig funded by the German Research Foundation (FZT 118). WDK acknowledges a Univ. of Amsterdam (UvA) starting grant. KB-G, DMD, ELN and MS received support from the research funding program ‘LOEWE – Landes-Offensive zur Entwicklung Wissenschaftlich-ökonomischer Exzellenz’ of Hesse’s Ministry of Higher Education, Research, and the Arts. DMD was also supported by a Marsden Fund Fast-Start Grant (UOC-1101) administered by the Royal Society of New Zealand. The study in Argentina was funded by CONICET (PIP 2009-1025 and 2014-592) and ANPCyT (PICT 2013-1280). The study in Colombia was funded by Rufford Small Grant for Nature Conservation (# 11042-1), and the Graduate Student Scholarship ‘Francisco José de Caldas’, COLCIENCIAS (Depto Administrativo de Ciencia, Tecnología e Innovación Republica de Colombia). The study in Ecuador was funded by the German Research Foundation (DFG) in the framework of the Research Unit 823-825 ‘Platform for Biodiversity and Ecosystem Monitoring and Research in South Ecuador’ (PAK 825/1; BO 1221/20-1). Permits – Permission for conducting research in Parque Sierra de San Javier was granted by the Univ. Nacional de Tucumán.
© 2018 The Authors
- avian frugivory
- bipartite network
- resource and consumer specialization