Projected impacts of climate change on functional diversity of frugivorous birds along a tropical elevational gradient

Climate change forces many species to move their ranges to higher latitudes or elevations. Resulting immigration or emigration of species might lead to functional changes, e.g., in the trait distribution and composition of ecological assemblages. Here, we combined approaches from biogeography (species distribution models; SDMs) and community ecology (functional diversity) to investigate potential effects of climate-driven range changes on frugivorous bird assemblages along a 3000 m elevational gradient in the tropical Andes. We used SDMs to model current and projected future occurrence probabilities of frugivorous bird species from the lowlands to the tree line. SDM-derived probabilities of occurrence were combined with traits relevant for seed dispersal of fleshy-fruited plants to calculate functional dispersion (FDis; a measure of functional diversity) for current and future bird assemblages. Comparisons of FDis between current and projected future assemblages showed consistent results across four dispersal scenarios, five climate models and two representative concentration pathways. Projections indicated a decrease of FDis in the lowlands, an increase of FDis at lower mid-elevations and little changes at high elevations. This suggests that functional dispersion responds differently to global warming at different elevational levels, likely modifying avian seed dispersal functions and plant regeneration in forest ecosystems along tropical mountains.Fil: 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; Argentina. German Centre for Integrative Biodiversity Research; Alemania. Martin Luther University Halle-Wittenberg; Alemania. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Kissling, W. Daniel. University of Amsterdam; Países BajosFil: Böhning-Gaese, Katrin. Goethe Universitat Frankfurt; Alemania. Senckenberg Biodiversity and Climate Research Centre; Alemania. German Centre for Integrative Biodiversity Research; AlemaniaFil: Hensen, Isabell. Martin Luther University Halle-Wittenberg; Alemania. German Centre for Integrative Biodiversity Research; AlemaniaFil: Kühn, Ingolf. Martin Luther University Halle-Wittenberg; Alemania. German Centre for Integrative Biodiversity Research; Alemania. Helmholtz Centre for Environmental Research. Department Community Ecology; AlemaniaFil: Nowak, Larissa. Goethe Universitat Frankfurt; Alemania. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Töpfer, Till. Zoological Research Museum Alexander Koenig. Section Ornithology; AlemaniaFil: Wiegand, Thorsten. Helmholtz Centre for Environmental Research. Department Community Ecology; Alemania. German Centre for Integrative Biodiversity Research; AlemaniaFil: Dehling, D. Matthias. University of Canterbury; Nueva Zelanda. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Schleuning, Matthias. Senckenberg Biodiversity and Climate Research Centre; Alemani