Global patterns of stream detritivore distribution: Implications for biodiversity loss in changing climates

Aim: We tested the hypothesis that shredder detritivores, a key trophic guild in stream ecosystems, are more diverse at higher latitudes, which has important ecological implications in the face of potential biodiversity losses that are expected as a result of climate change. We also explored the dependence of local shredder diversity on the regional species pool across latitudes, and examined the influence of environmental factors on shredder diversity. Location: World‐wide (156 sites from 17 regions located in all inhabited continents at latitudes ranging from 67° N to 41° S). Methods: We used linear regression to examine the latitudinal variation in shredder diversity at different spatial scales: alpha (α), gamma (γ) and beta (β) diversity. We also explored the effect of γ‐diversity on α‐diversity across latitudes with regression analysis, and the possible influence of local environmental factors on shredder diversity with simple correlations. Results: Alpha diversity increased with latitude, while γ‐ and β‐diversity showed no clear latitudinal pattern. Temperate sites showed a linear relationship between γ‐ and α‐diversity; in contrast, tropical sites showed evidence of local species saturation, which may explain why the latitudinal gradient in α‐diversity is not accompanied by a gradient in γ‐diversity. Alpha diversity was related to several local habitat characteristics, but γ‐ and β‐diversity were not related to any of the environmental factors measured. Main: conclusions Our results indicate that global patterns of shredder diversity are complex and depend on spatial scale. However, we can draw several conclusions that have important ecological implications. Alpha diversity is limited at tropical sites by local factors, implying a higher risk of loss of key species or the whole shredder guild (the latter implying the loss of trophic diversity). Even if regional species pools are not particularly species poor in the tropics, colonization from adjacent sites may be limited. Moreover, many shredder species belong to cool‐adapted taxa that may be close to their thermal maxima in the tropics, which makes them more vulnerable to climate warming. Our results suggest that tropical streams require specific scientific attention and conservation efforts to prevent loss of shredder biodiversity and serious alteration of ecosystem processes.Fil: Boyero, Luz. James Cook University; Australia. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Pearson, Richard G.. James Cook University; AustraliaFil: Dudgeon, David. University of Hong Kong; ChinaFil: Ferreira, Verónica. Universidad de Coimbra; PortugalFil: Graca, Manuel A. S.. Universidad de Coimbra; PortugalFil: Gessner, Mark O.. Swiss Federal Institute of Aquatic Science and Technology; SuizaFil: Boulton, Andrew J.. University of New England; AustraliaFil: Chauvet, Eric. Université de Toulouse; FranciaFil: Yule, Catherine M.. Monash University; AustraliaFil: Albariño, Ricardo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Ramírez, Alonso. Universidad de Puerto Rico; Puerto RicoFil: Helson, Julie E.. University of Toronto; CanadáFil: Callisto, Marcos. Universidade Federal de Minas Gerais; BrasilFil: Arunachalam, Muthukumarasamy. Manonmainam Sundaranar University; IndiaFil: Chará, Julián. Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria; Colombia. Centro de Investigaciones y Estudios en Biodiversidad y Recursos Genéticos; ColombiaFil: Figueroa, Ricardo. Universidad de Concepción; ChileFil: Mathooko, Jude M.. Egerton University; KeniaFil: Goncalves Jr, José F.. Universidade Federal de Minas Gerais; BrasilFil: Moretti, Marcelo S.. Universidade Federal de Minas Gerais; BrasilFil: Chará Serna, Ana Marcela. Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria; Colombia. Centro de Investigaciones y Estudios en Biodiversidad y Recursos Genéticos; ColombiaFil: Davies, Judy N.. University of New England; AustraliaFil: Encalada, Andrea C.. Universidad de Coimbra; PortugalFil: Lamothe, Sylvain. Université de Toulouse; FranciaFil: Buria, Leonardo Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Castela, José. Universidad de Coimbra; PortugalFil: Cornejo, Aydeé. Universidad de Panamá; PanamáFil: Li, Aggie O. Y.. University of Hong Kong; ChinaFil: M´Erimba, Charles. Egerton University; KeniaFil: Diaz Villanueva, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Zúñiga, María del Carmen. Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria; Colombia. Centro de Investigaciones y Estudios en Biodiversidad y Recursos Genéticos; ColombiaFil: Swan, Christopher M.. University of Maryland; Estados UnidosFil: Barmuta, León A.. University of Tasmania; Australi