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Author:
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Sebastián-González, Esther; Morales-Reyes, Zebensui; Botella, Francisco; Naves-Alegre, Lara; Pérez-García, Juan M.; Mateo-Tomás, Patricia; Olea, Pedro P.; Moleón, Marcos; Barbosa, Jomar M.; Hiraldo, Fernando; Arrondo, Eneko; Donázar, José A.; Cortés-Avizanda, Ainara; Selva, Nuria; Lambertucci, Sergio A.; Bhattacharjee, Aishwarya; Brewer, Alexis L.; Abernethy, Erin F.; Turner, Kelsey L.; Beasley, James C.; DeVault, Travis L.; Gerke, Hannah C.; Rhodes Jr, Olin E.; Ordiz, Andrés; Wikenros, Camilla; Zimmermann, Barbara; Wabakken, Petter; Wilmers, Christopher C.; Smith, Justine A.; Kendall, Corinne J.; Ogada, Darcy; Frehner, Ethan; Allen, Maximilian L.; Wittmer, Heiko U.; Butler, James R. A.; Du Toit, Johan T.; Margalida, Antoni; Oliva-Vidal, Pilar; Wilson, David; Jerina, Klemen; Krofel, Miha; Kostecke, Rich; Inger, Richard; Per, Esra; Ayhan, Yunus; Ulusoy, Hasan; Vural, Doğanay; Inagaki, Akino; Koike, Shinsuke; Samson, Arockianathan; Perrig, Paula L.; Spencer, Emma; Newsome, Thomas M.; Heurich, Marco; Anadón, José D.; Buechley, Evan R.; Sánchez-Zapata, José Antonio
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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.
ESG, JMB and JMPG were supported by Juan de la Cierva contracts (Ministerio de Economía y Competitividad, MEC; IJCI‐2015‐24947, IJCI‐2017‐32149 and FJCI‐2015‐25632, respectively). ESG and LNA were also supported by Generalitat Valenciana (SEJI/2018/024 and ACIF/2019/056, respectively), ACA by the Govern de les Illes Balears (PD/039/2017) and MM by a Ramón y Cajal contract (MEC; RYC‐2015‐19231). EA was supported by La Caixa‐Severo Ochoa International PhD Program 2015, ZMR by a postdoctoral contract co‐funded by the Generalitat Valenciana and the European Social Fund (APOSTD/2019/016). NS was partly supported by the National Science Centre in Poland (2013/08/M/NZ9/00469 and 2016/22/Z/NZ8/00). SAL thanks PICT (BID) 0725/2014. MK and KJ were supported by the Slovenian Research Agency (P4‐0059) and EU Life DinAlp Bear (LIFE13 NAT/SI/000550). Contributions of HG, KLT, EFA, OER, TLD and JCB were partially supported through funding from U.S. Dept of Agriculture and the U.S. Dept of Energy under (DE‐EM0004391) to the Univ. of Georgia Research Foundation. HG was also supported by the Inst. of Environmental Radioactivity at Fukushima Univ. ALB and JDA were partially supported by Queens College and the Graduate Center at the City Univ. of New York. JDA is currently supported by a Ramón y Cajal contract (RYC‐2017‐22783) co‐funded by the Spanish Ministry of Science, the Agencia Estatal de Investigación and the European Social Fund. ERB and EF were supported by the USA National Science Foundation Graduate Research Fellowship (1256065). CK completed study with support from Hawk Mountain Sanctuary, The Peregrine Fund, and via Pompeo M. Maresi Memorial Fund via Princeton Univ. JAS and CCW were supported by the USA National Science Foundation #1255913, the American Association for Univ. Women and the Gordon and Betty Moore Foundation. HUW acknowledges funding from the California Dept of Fish and Wildlife (P0880013). PLP was supported by the Rufford Foundation and Univ. of Wisconsin‐Madison. JB and JdT thank the Percy Sladen Memorial Fund and Mr Rodney Fuhr. Several authors were funded by funds from the MEC (CGL2012‐40013‐C02‐01/02, CGL2015‐66966‐C2‐1‐R, CGL2015‐66966‐C2‐1‐R2, CGL2017‐89905‐R and RTI2018‐099609‐B‐C22) and from the Junta de Andalucía (RNM‐1925). POV was supported by a research contract by the Univ. of Lleida. ES and TMN were funded and supported by Australian Geographic, Bush Heritage Australia, Australian Academy of Sciences, Ecological Society of Australia, NSW Office of Environment and Heritage, and Emirates Wolgan Valley One and Only Resort. |
