title: Stability and generalization in seed dispersal networks: a case study of frugivorous fish in Neotropical wetlands.
abstract: When species within guilds perform similar ecological roles, functional redundancy can buffer ecosystems against species loss. Using data on the frequency of interactions between fish and fruit, we assessed whether co-occurring frugivores provide redundant seed dispersal services in three species-rich Neotropical wetlands. Our study revealed that frugivorous fishes have generalized diets; however, large-bodied fishes had greater seed dispersal breadth than small species, in some cases, providing seed dispersal services not achieved by smaller fish species. As overfishing disproportionately affects big fishes, the extirpation of these species could cause larger secondary extinctions of plant species than the loss of small specialist frugivores. To evaluate the consequences of frugivore specialization for network stability, we extracted data from 39 published seed dispersal networks of frugivorous birds, mammals and fish (our networks) across ecosystems. Our analysis of interaction frequencies revealed low frugivore specialization and lower nestedness than analyses based on binary data (presence-absence of interactions). In that case, ecosystems may be resilient to loss of any given frugivore. However, robustness to frugivore extinction declines with specialization, such that networks composed primarily of specialist frugivores are highly susceptible to the loss of generalists. In contrast with analyses of binary data, recently developed algorithms capable of modelling interaction strengths provide opportunities to enhance our understanding of complex ecological networks by accounting for heterogeneity of frugivore-fruit interactions.
authors: Odum School of Ecology, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors: Sandra Bibiana
authors: 0000-0003-4466-6923
authors: SB
authors: Correa
authors: Centro de Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Av. Fernando Correia 2367, Cuiabá, MT, Brazil.
authors: Joisiane K
authors: JK
authors: Arujo
authors: Centro de Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Av. Fernando Correia 2367, Cuiabá, MT, Brazil.
authors: Jerry
authors: J
authors: Penha
authors: Centro de Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Av. Fernando Correia 2367, Cuiabá, MT, Brazil.
authors: Catia
authors: C
authors: Nunes da Cunha
authors: Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors: Karen E
authors: 0000-0002-4050-2078
authors: KE
authors: Bobier
authors: Odum School of Ecology, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA jta24@uga.edu.
authors: Jill T
authors: 0000-0002-3253-8142
authors: JT
authors: Anderson
mesh_terms: D000818:Animals; D004032:Diet / Q000662:veterinary*; D017753:Ecosystem; D005399:Fishes; D005638:Fruit; D058614:Seed Dispersal; D014329:Tropical Climate; D053833:Wetlands
keywords: frugivorous fish; functional redundancy; nestedness; network modularity; robustness; specialization