DOI: 10.6084/m9.figshare.14605581.v1
title: Data on: Modelling selection, drift, dispersal and their interactions in the community assembly of Amazonian soil mites

description: Data on species abundance, species traits and environmental variables for 55 sites sampled over a lowland rainforest landscape in central Amazonia, Brazil.<br> Files "Oribatida_Ducke_55.csv", "Traits_Ducke_55.csv", and "Environment_Ducke_55.csv" provide the raw community, trait and environmental data used in the study, respectively. File "ESM2_Oeco.doc" provides a short description of the R script used to analyze the data, and file "Metacommunity_Rscript_dataS1_Oeco.R" is a commented R script containing all analyzes performed.<br> The data were obtained as part of the Brazilian Program for Biodiversity Research (PPBio) in Reserva Ducke, a large reserve of primary tropical rainforest (10 x 10 km) in Manaus, Brazil (2°57’S, 59°56’W) (Costa and Magnusson 2010). The reserve is under administration of the National Institute for Amazonia Research (INPA). Mite sampling was carried out from March 18 to May 13, 2002. Mites were collected from 55 sites distributed over a grid in the reserve, with at least 1 km between them. On each site, one 250-m transect was established along a topographic contour lines, in order to minimize environmental variation within it. Then, one soil core (3.5 cm x 3.5 cm x 5 cm) was sampled each 12.5 m along the transect, with 20 cores per transect and 55 sites × 20 cores = 1100 cores overall. Within-site soil cores thus provided a representative sample of the local, site-level community, which was the sampling unit of the study. To reduce the large sample processing load, each four consecutive soil cores within transects were combined as a compound soil sample. Compound samples were kept in plastic containers and transported to the Laboratory of Systematics and Ecology of Terrestrial Arthropods at INPA’s campus in Manaus, where animals were extracted using a Berlese-Tullgren apparatus. Samples were gradually heated from 28 to 45 ºC until they were completely dry, which took from six to seven days. Extracted animals were preserved in glass vials containing 4% formaldehyde solution. All adult oribatid mites were sorted to morphospecies and identified whenever possible using taxonomic keys. Identification proceeded by clarifying specimens with lactic acid, followed by temporary slide-mounting and examination under a compound microscope. Immatures were not considered, but represented only 8% of extracted individuals. Voucher specimens were deposited in the Entomological Collection of INPA.<br> We estimated the mean body mass of each sampled species by measuring 1–15 individuals of each sampled species, depending on their abundance. For each individual, body length and width (µm) were measured under a microscope, and body mass (µg) was predicted using a well-established allometric equation (<i>R²</i> = 0.98; Caruso and Migliorini 2009): mass = -17.17 + 3.0log(length+width). Then, the mean body mass was calculated for each species. Species reproductive mode (sexual or parthenogenetic) was inferred using published records. When a species’ reproductive mode was unknown (i.e. morphospecies with a single individual), it was inferred from closely related species, if part of a taxonomic group that is not known to vary in reproductive mode. Otherwise, the species was assumed to be sexual.<br> Data were obtained on soil texture (clay content, in %), soil contents of water (%) and nutrients (C, N and P, in g kg<sup>-1</sup>) and litter dry mass (g). Litter dry mass was measured during mite surveys by marking 50 x 50 cm squares along transects, one each 50 m, within which all litter was harvested. Litter samples were transported to the laboratory in plastic containers and dried to constant weight. Further, in each transect, six soil cores (one each 50 m) were collected to a depth of 5 cm. Soil cores were pooled in a plastic container and transported to INPA for granulometric analysis, and to the Brazilian Agricultural Research Corporation (EMBRAPA), also in Manaus, for nutrient analyses. Soil samples were oven-dried, cleaned of stones and roots, and passed through a 2 mm sieve. Soil granulometry was determined using the hydrometer method (clay: &lt;0.002 mm; silt: 0.002–0.05 mm; sand: 0.05–2 mm). As clay and sand contents were highly correlated (<i>r</i> = -0.99) and silt content was negligible, we used clay to describe soil texture. Total organic carbon was measured by wet oxidation, using acid dichromate solution followed by titration with 0.5N FeSO<sub>4</sub> and o-phenalphthroline. Total nitrogen was estimated using the wet oxidation (Kjeldahl method), by converting organic N to ammonium (NH4+) for measurement. Available phosphorus was estimated using the ammonium molybdate–ascorbic acid method, by reading the blue complex formed at 712 nm under a spectrophotometer. Soil water content was obtained by comparison between the wet and dry weights of soil samples. Soil and litter measurements were averaged by site.<br> References: <br>Caruso T, Migliorini M (2009) Euclidean geometry explains why lengths allow precise body mass estimates in terrestrial invertebrates: the case of oribatid mites. J Theor Biol 256:436–40. doi: 10.1016/j.jtbi.2008.09.033 <br>Costa FRC, Magnusson WE (2010) The need for large-scale, integrated studies of biodiversity – the experience of the Program for Biodiversity Research in Brazilian Amazonia. Brazilian J Nat Conserv 8:3–12.