Network structure of vertebrate scavenger assemblages at the global scale: drivers and ecosystem functioning implications
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CarrionConsumption rateEcological networksglobal changeMacroecologyNDVI
Sebastián‐González, E. et al. (2020). Network structure of vertebrate scavenger assemblages at the global scale: drivers and ecosystem functioning implications. Ecography. [https://doi.org/10.1111/ecog.05083]
SponsorshipJuan de la Cierva contracts (Ministerio de Economia y Competitividad, MEC) IJCI-2015-24947 IJCI-2017-32149 FJCI-2015-25632; Generalitat Valenciana SEJI/2018/024 ACIF/2019/056; Govern de les Illes Balears PD/039/2017; Spanish Government RYC-2015-19231; La Caixa-Severo Ochoa International PhD Program 2015; European Social Fund (ESF) APOSTD/2019/016; National Science Centre in Poland 2013/08/M/NZ9/00469 2016/22/Z/NZ8/00; ANPCyT (BID) 0725/2014; Slovenian Research Agency - Slovenia P4-0059; EU Life DinAlp Bear LIFE13 NAT/SI/000550; United States Department of Agriculture (USDA) DE-EM0004391; United States Department of Energy (DOE) DE-EM0004391; Inst. of Environmental Radioactivity at Fukushima Univ.; Queens College at the City Univ. of New York; Graduate Center at the City Univ. of New York; Ramón y Cajal contract - Spanish Ministry of Science RYC-2017-22783; Agencia Estatal de Investigacion; European Social Fund (ESF); USA National Science Foundation Graduate Research Fellowship 1256065; Hawk Mountain Sanctuary, The Peregrine Fund, and via Pompeo M. Maresi Memorial Fund via Princeton Univ.; National Science Foundation (NSF) 1255913; American Association for Univ. Women; Gordon and Betty Moore Foundation; California Dept of Fish and Wildlife P0880013; Rufford Foundation; Univ. of Wisconsin-Madison; Percy Sladen Memorial Fund; Spanish Government CGL201240013-C02-01/02 CGL2015-66966-C2-1-R CGL2015-66966C2-1-R2 CGL2017-89905-R RTI2018-099609-B-C22; Junta de Andalucía RNM-1925; Univ. of Lleida; Australian Geographic; Bush Heritage Australia; Australian Academy of Sciences; Ecological Society of Australia; NSW Office of Environment and Heritage; Emirates Wolgan Valley One and Only Resort
The organization of ecological assemblages has important implications for ecosystem functioning, but little is known about how scavenger communities organize at the global scale. Here, we test four hypotheses on the factors affecting the network structure of terrestrial vertebrate scavenger assemblages and its implications on ecosystem functioning. We expect scavenger assemblages to be more nested (i.e. structured): 1) in species‐rich and productive regions, as nestedness has been linked to high competition for carrion resources, and 2) regions with low human impact, because the most efficient carrion consumers that promote nestedness are large vertebrate scavengers, which are especially sensitive to human persecution. 3) We also expect climatic conditions to affect assemblage structure, because some scavenger assemblages have been shown to be more nested in colder months. Finally, 4) we expect more organized assemblages to be more efficient in the consumption of the resource. We first analyzed the relationship between the nestedness of the scavenger assemblages and climatic variables (i.e. temperature, precipitation, temperature variability and precipitation variability), ecosystem productivity and biomass (i.e. NDVI) and degree of human impact (i.e. human footprint) using 53 study sites in 22 countries across five continents. Then, we related structure (i.e. nestedness) with its function (i.e. carrion consumption rate). We found a more nested structure for scavenger assemblages in regions with higher NDVI values and lower human footprint. Moreover, more organized assemblages were more efficient in the consumption of carrion. However, our results did not support the prediction that the structure of the scavenger assemblages is directly related to climate. Our findings suggest that the nested structure of vertebrate scavenger assemblages affects its functionality and is driven by anthropogenic disturbance and ecosystem productivity worldwide. Disarray of scavenger assemblage structure by anthropogenic disturbance may lead to decreases in functionality of the terrestrial ecosystems via loss of key species and trophic facilitation processes.