Similar composition of functional roles in Andean seed-dispersal networks, despite high species and interaction turnover

The species composition of local communities varies in space, and its similarity generally decreases with increasing geographic distance between communities, a phenomenon known as distance decay of similarity. It is, however, not known how changes in local species composition affect ecological processes, that is, whether they lead to differences in the local composition of species' functional roles. We studied eight seed-dispersal networks along the South American Andes and compared them with regard to their species composition and their composition of functional roles. We tested (1) if changes in bird species composition lead to changes in the composition of bird functional roles, and (2) if the similarity in species composition and functional-role composition decreased with increasing geographic distance between the networks. We also used cluster analysis to (3) identify bird species with similar roles across all networks based on the similarity in the plants they consume, (i) considering only the species identity of the plants and (ii) considering the functional traits of the plants. Despite strong changes in species composition, the networks along the Andes showed similar composition of functional roles. (1) Changes in species composition generally did not lead to changes in the composition of functional roles. (2) Similarity in species composition, but not functional-role composition, decreased with increasing geographic distance between the networks. (3) The cluster analysis considering the functional traits of plants identified bird species with similar functional roles across all networks. The similarity in functional roles despite the high species turnover suggests that the ecological process of seed dispersal is organized similarly along the Andes, with similar functional roles fulfilled locally by different sets of species. The high species turnover, relative to functional turnover, also indicates that a large number of bird species are needed to maintain the seed-dispersal process along the Andes.Fil: Dehling, D. Matthias. University of Canterbury; Nueva ZelandaFil: Peralta, Guadalupe. University of Canterbury; Nueva ZelandaFil: Bender, Irene Maria Antoinetta. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Böhning Gaese, Katrin. Goethe Universitat Frankfurt; AlemaniaFil: Muñoz, Marcia C.. Universidad de la Salle; ColombiaFil: Neuschulz, Eike Lena. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Quitián, Marta. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Saavedra, Francisco. Universidad Mayor de San Andrés; BoliviaFil: Santillán, Vinicio. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Schleuning, Matthias. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Stouffer, Daniel B.. University of Canterbury; Nueva Zeland

Specialists and generalists fulfil important and complementary functional roles in ecological processes

Species differ in their resource use and their interactions with other species and, consequently, they fulfil different functional roles in ecological processes. Species with specialized functional roles (specialists) are considered important for communities because they often interact with species with which few other species interact, thereby contributing complementary functional roles to ecological processes. However, the contribution of specialists could be low if they only interact with a small range of interaction partners. In contrast, species with unspecialized functional roles (generalists) often do not fulfil complementary roles but their contribution to ecological processes could be high because they interact with a large range of species. To investigate the importance of the functional roles of specialists versus generalists, we tested the relationship between species' degree of specialization and their contribution to functional-role diversity for frugivorous birds in Andean seed-dispersal networks. We used two measures for the specialization of birds—one based on the size, and one based on the position of their interaction niche—and measured their effect on the birds' contribution to functional-role diversity and their functional complementarity, a measure of how much a species' functional role is complementary to those of the other species. In all networks, there were similar log-normal distributions of species' contributions to functional-role diversity and functional complementarity. Contribution to functional-role diversity and functional complementarity increased with both increasing niche-position specialization and increasing niche size, indicating that the composition of functional roles in the networks was determined by an interplay between specialization and generalization. There was a negative interaction between niche-position specialization and niche size in both models, which showed that the positive effect of niche-position specialization on functional-role diversity and functional complementarity was stronger for species with a small niche size, and vice versa. Our results show that there is a continuum from specialized to generalized functional roles in species communities, and that both specialists and generalists fulfil important functional roles in ecological processes. Combining interaction networks with functional traits, as exemplified in this study, provides insight into the importance of an interplay of redundancy and complementarity in species' functional roles for ecosystem functioning. A free Plain-Language Summary can be found within the Supporting Information of this article.Fil: Dehling, Matthias. University of Canterbury; Nueva Zelanda. Eidgenössische Forschungsanstalt Für Wald, Schnee Und Landschaft Wsl; SuizaFil: Bender, Irene Maria Antoinetta. Senckenberg Biodiversität Und Klima Forschungszentrum; Alemania. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Böhning Gaese, Katrin. Goethe Universitat Frankfurt; Alemania. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Muñoz, Marcia C.. Universidad de la Salle, Bogota; ColombiaFil: Neuschulz, Eike L.. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Quitián, Marta. Tokyo Metropolitan University; JapónFil: Saavedra, Francisco. Universidad Mayor de San Andrés; BoliviaFil: Santillán, Vinicio. Universidad Católica de Cuenca; EcuadorFil: Schleuning, Matthias. Senckenberg Biodiversität Und Klima Forschungszentrum; AlemaniaFil: Stouffer, Daniel B.. University of Canterbury; Nueva Zeland

Nutrient balance and energy-acquisition effectiveness: Do birds adjust their fruit diet to achieve intake targets?

According to diet-regulation hypotheses, animals select food to regulate the intake of macronutrients or maximise energy feeding efficiency. Specifically, the nutrient balance model proposes that foraging is primarily a process of balancing multiple nutrients to achieve a nutritional intake target, while the energy maximisation model proposes that foraging aims to maximise energy. Here, we evaluate the adjustment of fruit diets (the fruit-derived component of the diets) to nutritional and energy intake targets, characterising the nutrient balance and energy maximisation strategies across fruit-eating bird species with different fruit-handling behaviours (‘gulpers’, which swallow whole fruits, and ‘mashers’, which process the fruit in the beak) in subtropical Andean forests. Food-handling behaviour determines the food intake rate and, consequently, influences animal efficiency to obtain nutrients and energy. We used extensive field data from the diet of fruit-eating birds to test how species adjust their food intake. We used nutritional geometry to explore macronutrient balance and the effectiveness framework to explore energy-acquisition effectiveness. Observed diets showed a good fit with predictions of a diet balanced in macronutrient proportions. With few exceptions, diets clustered near an optimal macronutrient mixture and did not differ from each other in terms of maximising energy intake. Moreover, when comparing our results with a random diet based on local fruit availability, birds tended to fit better to the nutritional target, and less to the energy target, than expected from a random diet. Fruit-handling behaviour did not affect the ability of bird species to reach a nutritional target but it affected species energy acquisition, which was lower in mashers than in gulpers. This study explores for the first time different diet-regulation strategies in wild fruit-eating birds, and supports the argument that the diet reflects a specific regulation of macronutrients. Understanding why birds select fruits is a complex question requiring multiple considerations. The nutrient balance model explains the relevance of nutrient composition in the fruit selection by fruit-eating birds, although it is still necessary to determine its relative importance with respect to other dietary drivers. Read the free Plain Language Summary for this article on the Journal blog.Fil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; ArgentinaFil: Rojas, Tobias Nicolas. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Ramírez Mejía, Andrés Felipe. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Bender, Irene Maria Antoinetta. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Lomascolo, Silvia Beatriz. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Magro, Julieta. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Nuñez Montellano, Maria Gabriela. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Ruggera, Román Alberto. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; ArgentinaFil: Valoy, Mariana Eugenia. Fundación Miguel Lillo; ArgentinaFil: Ordano, Mariano Andrés. Fundación Miguel Lillo; Argentina. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentin

Trait-Based Assessments of Climate-Change Impacts on Interacting Species

Plant–animal interactions are fundamentally important in ecosystems, but have often been ignored by studies of climate-change impacts on biodiversity. Here, we present a trait-based framework for predicting the responses of interacting plants and animals to climate change. We distinguish three pathways along which climate change can impact interacting species in ecological communities: (i) spatial and temporal mismatches in the occurrence and abundance of species, (ii) the formation of novel interactions and secondary extinctions, and (iii) alterations of the dispersal ability of plants. These pathways are mediated by three kinds of functional traits: response traits, matching traits, and dispersal traits. We propose that incorporating these traits into predictive models will improve assessments of the responses of interacting species to climate change.Fil: Schleuning, Matthias. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Neuschulz, Eike Lena. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Albrecht, Jörg. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Bender, Irene Maria Antoinetta. German Centre for Integrative Biodiversity Research; Alemania. Senckenberg Biodiversity and Climate Research Centre; Alemania. Martin-Luther University. Institute of Biology, Geobotany and Botanical Garden; AlemaniaFil: Bowler, Diana E.. German Centre for Integrative Biodiversity Research; Alemania. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Dehling, D. Matthias. University of Canterbury; Nueva ZelandaFil: Fritz, Susanne A.. Goethe Universitat Frankfurt; Alemania. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Hof, Christian. Universitat Technical Zu Munich; Alemania. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Mueller, Thomas. Goethe Universitat Frankfurt; Alemania. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Nowak, Larissa. Goethe Universitat Frankfurt; Alemania. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Sorensen, Marjorie C.. Goethe Universitat Frankfurt; Alemania. University of Guelph; Canadá. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Böhning Gaese, Katrin. Goethe Universitat Frankfurt; Alemania. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Kissling, W. Daniel. University of Amsterdam; Países Bajo