title: The influence of environmental, biotic and spatial factors on diatom metacommunity structure in Swedish headwater streams.
abstract: Stream assemblages are structured by a combination of local (environmental filtering and biotic interactions) and regional factors (e.g., dispersal related processes). The relative importance of environmental and spatial (i.e., regional) factors structuring stream assemblages has been frequently assessed in previous large-scale studies, but biotic predictors (potentially reflecting local biotic interactions) have rarely been included. Diatoms may be useful for studying the effect of trophic interactions on community structure since: (1) a majority of experimental studies shows significant grazing effects on diatom species composition, and (2) assemblages can be divided into guilds that have different susceptibility to grazing. We used a dataset from boreal headwater streams in south-central Sweden (covering a spatial extent of ∼14000 km(2)), which included information about diatom taxonomic composition, abundance of invertebrate grazers (biotic factor), environmental (physicochemical) and spatial factors (obtained through spatial eigenfunction analyses). We assessed the relative importance of environmental, biotic, and spatial factors structuring diatom assemblages, and performed separate analyses on different diatom guilds. Our results showed that the diatom assemblages were mainly structured by environmental factors. However, unique spatial and biological gradients, specific to different guilds and unrelated to each other, were also evident. We conclude that biological predictors, in combination with environmental and spatial variables, can reveal a more complete picture of the local vs. regional control of species assemblages in lotic environments. Biotic factors should therefore not be overlooked in applied research since they can capture additional local control and therefore increase accuracy and performance of predictive models. The inclusion of biotic predictors did, however, not significantly influence the unique fraction explained by spatial factors, which suggests low bias in previous assessments of unique regional control of stream assemblages.
authors: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden. emma.gothe@gmail.com
authors: Emma
authors: E
authors: Göthe
authors: David G
authors: DG
authors: Angeler
authors: Steffi
authors: S
authors: Gottschalk
authors: Stefan
authors: S
authors: Löfgren
authors: Leonard
authors: L
authors: Sandin
mesh_terms: D044822:Biodiversity; D017377:Diatoms / Q000145:classification; D017753:Ecosystem; D004777:Environment; D005843:Geography; D011157:Population Dynamics; D045483:Rivers; D062206:Spatial Analysis; D013548:Sweden
references: Science. 2002 May 10;296(5570):1061-3
references: 12004115
references: Ecology. 1987 Dec;68(6):1955-1965
references: 29357163
references: J Anim Ecol. 2006 Mar;75(2):476-84
references: 16638000
references: Am Nat. 2003 Nov;162(5):544-57
references: 14618534
references: J Anim Ecol. 2013 Mar;82(2):449-58
references: 23163593
references: Oecologia. 1983 Jun;58(3):378-382
references: 28310338
references: Ecol Lett. 2012 Jul;15(7):740-7
references: 22583795
references: J Anim Ecol. 2010 May;79(3):571-80
references: 20180874
references: Oecologia. 2009 Feb;159(1):151-9
references: 18941791
references: Annu Rev Entomol. 1998;43:271-93
references: 15012391
references: Ecol Appl. 2010 Jun;20(4):978-92
references: 20597284
references: Oecologia. 2001 Oct;129(2):271-280
references: 28547606
references: Ambio. 2011 Dec;40(8):836-56
references: 22201000
references: Oecologia. 2011 Jun;166(2):357-68
references: 21170750
references: Protist. 2002 Sep;153(3):261-73
references: 12389815
references: Biol Rev Camb Philos Soc. 2013 Feb;88(1):166-78
references: 22937892
references: Am Nat. 2002 Apr;159(4):420-6
references: 18707425
references: Ecol Lett. 2012 Mar;15(3):218-26
references: 22221744