A comparative analysis reveals weak relationships between ecological factors and beta diversity of stream insect metacommunities at two spatial levels

The hypotheses that beta diversity should increase with decreasing latitude and increase with spatial extent of a region have rarely been tested based on a comparative analysis of multiple datasets, and no such study has focused on stream insects. We first assessed how well variability in beta diversity of stream insect metacommunities is predicted by insect group, latitude, spatial extent, altitudinal range, and dataset properties across multiple drainage basins throughout the world. Second, we assessed the relative roles of environmental and spatial factors in driving variation in assemblage composition within each drainage basin. Our analyses were based on a dataset of 95 stream insect metacommunities from 31 drainage basins distributed around the world. We used dissimilarity-based indices to quantify beta diversity for each metacommunity and, subsequently, regressed beta diversity on insect group, latitude, spatial extent, altitudinal range, and dataset properties (e.g., number of sites and percentage of presences). Within each metacommunity, we used a combination of spatial eigenfunction analyses and partial redundancy analysis to partition variation in assemblage structure into environmental, shared, spatial, and unexplained fractions. We found that dataset properties were more important predictors of beta diversity than ecological and geographical factors across multiple drainage basins. In the within-basin analyses, environmental and spatial variables were generally poor predictors of variation in assemblage composition. Our results revealed deviation from general biodiversity patterns because beta diversity did not show the expected decreasing trend with latitude. Our results also call for reconsideration of just how predictable stream assemblages are along ecological gradients, with implications for environmental assessment and conservation decisions. Our findings may also be applicable to other dynamic systems where predictability is low.Fil: Heino, Jani. Natural Environment Centre; FinlandiaFil: Melo, Adriano S.. Universidade Federal de Goias; BrasilFil: Bini, Luis Mauricio. Universidade Federal de Goias; BrasilFil: Altermatt, Florian. Eawag: Swiss Federal Institute of Aquatic Science and Technology; Suiza. Institute of Evolutionary Biology and Environmental Studies; SuizaFil: Al-Shami, Salman A.. Universiti Sains Malaysia; Malasia.  University of Tabuk; Arabia SauditaFil: Angeler, David G.. Swedish University of Agricultural Sciences; SueciaFil: Bonada, Núria. Universidad de Barcelona; EspañaFil: Brand, Cecilia. Universidad Nacional de la Patagonia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Callisto, Marcos. Universidade Federal de Minas Gerais; BrasilFil: Cottenie, Karl.  University of Guelph; CanadáFil: Dangles, Olivier. Pontifical Catholic University of Ecuador; Ecuador.  Laboratoire Evolution, Génomes et Spéciation; FranciaFil: Dudgeon, David.  The University of Hong Kong; ChinaFil: Encalada, Andrea.  Universidad San Francisco de Quito; EcuadorFil: Göthe, Emma. Aarhus University; DinamarcaFil: Grönroos, Mira.  Natural Environment Centre; FinlandiaFil: Hamada, Neusa. Instituto Nacional de Pesquisas da Amazónia; BrasilFil: Jacobsen, Dean. University of Copenhagen; DinamarcaFil: Landeiro, Victor L.. Universidade Federal do Mato Grosso; BrasilFil: Ligeiro, Raphael. Universidade Federal de Minas Gerais; BrasilFil: Martins, Renato T.. Instituto Nacional de Pesquisas da Amazónia; BrasilFil: Miserendino, Maria Laura. Universidad Nacional de la Patagonia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Md Rawi, Che Salmah.  Universiti Sains Malaysia; MalasiaFil: Rodrigues, Marciel E.. Universidade Federal do Mato Grosso Do Sul; BrasilFil: de Oliveira Roque, Fabio. Universidade Federal do Mato Grosso Do Sul; BrasilFil: Sandin, Leonard. Swedish University of Agricultural Sciences; SueciaFil: Schmera, Denes. University of Basel; Suiza. Hungarian Academy of Sciences; HungríaFil: Sgarbi, Luciano F.. Universidade Federal de Goias; BrasilFil: Simaika, John P.. Stellenbosch University; SudáfricaFil: Siqueira, Tadeu. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Thompson, Ross M.. University of Canberra; AustraliaFil: Townsend, Colin R.. University Of Otago; Nueva Zeland