Data from: Testing trade-offs and the dominance-impoverishment rule among ant communities

We conducted baiting experiments at 40 sites of 20 x 20 m (each consisting of four 5 x 5 m subplots) during the daytime between June 29th and November 11th 2016 at 40 sites: 20 in Spain, seven in France, five in Germany, three in Denmark, four in the United States, and one in French Guiana (Fig. 1). Sites were in areas with known ant activity or where ant fieldwork had previously been carried out and spanned a range of ecological biomes, including temperate forests, deserts and xeric shrublands and rainforests. Sites were separated by at least 100 m. We designed the experiments similarly to classic experiments in ant ecology (Fellers, 1987; Savolainen & Vepsalainen, 1988; Savolainen, Vepsäläinen & Wuorenrinne, 1989; Andersen, 1992; Perfecto, 1994; Cerdá et al. 1997; Sanders & Gordon, 2003). Specifically, we chose five different resources (canned tuna in water, untoasted sesame seeds, 20 % sugar water solution, 1 % saltwater solution and tap water) to attract diverse species at each site. Approximately one teaspoon of solid resources and 2.5 cm diameter cotton balls soaked in the liquid resources were placed on individual ~6 cm diameter plastic discs in the middle of each subplot in a pentagonal shape, equidistant from the plot boundaries and approximately 20 cm from each other. Twenty baits were deployed at each site: One bait per bait type (5) per subplot (4). After deploying the baits, the numbers and identities of ants present were recorded after 5, 15, 30, 60, 90 and 120 minutes. Ground temperatures were measured during each observation using a handheld infrared thermometer (Raytek Raynger ST). Ants were identified to species or morpho-species either in the field or in the lab. We extracted four environmental variables from online databases for each site. Mean annual temperature (MAT) and annual precipitation (AP) data were extracted from the 1970-2000 average WorldClim2 dataset at a resolution of 30 arc seconds (Fick & Hijmans, 2017). We extracted monthly normalised difference vegetation index (NDVI) values for each site during the month when sampling occurred from Moderate-Resolution Imaging Spectroradiometer MOD17, 30-arcsec data (Didan, 2015). We estimated actual evapotranspiration (AET) using Turc’s formula (Turc, 1954; Kluge et al., 2006; Sanders, Dunn, Fitzpatrick, Carlton, Pogue, Parker & Simons, 2009), where AET = P/[0.9 + ( P/L)2]1/2 with L = 300 + 25T + 0.05T3, P = annual precipitation and T = annual mean temperature.