Gijsbert Werner, Department of Ecological Science, Vrije Universiteit Amsterdam. For questions and remarks, please contact g.d.a.werner@vu.nl File Description WernerNfix.csv. This file contains the full symbiotic N2-fixation database we compiled, a subset of which was analysed in Werner et al. (2014). For those species that were analysed in Werner et al. (2014), analysis results can be found in the Supplementary Data 2 to Werner et al. (2014). Please note that manual evaluation of reliability of N2-fixation reports, and of species names, was only performed for those species that were analysed in Werner et al. (2014). For all other species, proceed with caution when using this database. Ideally, verify reports, particularly for influential data points and perform analyses to account for sensitivity of results to data errors (see Methods Werner et al. (2014)). Even for the manually evaluated species, no guarantees regarding the reliability of data points can be given. Again, be careful in interpreting results, and consider performing analyses to account for sensitivity to errors in the data. Full references to all data sources, including all TRY data contributors and associated references, can be found below under 'Data References' and in Werner et al. (2014), Supplementary Table 3, and. Description of variables Species: Genus and species name NFC: Is the species in the Nitrogen-Fixing Clade (Soltis et al. 1995)? Legume: Is the species a legume? Order: Order of the species Family: Family of the species Data_fixing: Does the species engage in symbiotic N2-fixation with bacterial N2-fixing symbionts (nodulation)? Source: Main source of the data: TRY, GRIN, Sprent2001, Sprent2009 or Manual (directly from primary literature), see Methods of Werner et al. 2014 for more information. Source2: Details on data source. In the case of TRY-data: last name of data contributor. GRIN: no further information. Sprent2001 & Sprent2009: Location of information in the volume. Manual: primary reference. See Table S3 in Werner et al. (2014) or below under Data References for full references. Data_corrected: Were reports of absence/presence of symbiotic N2-fixation corrected after manual evaluation of the reliability of the report? Species_corrected: Were species names corrected following suggestions from the the Taxonomic Name Resolution Service (TNRS), or after manual evaluation? Analysed_Werner_etal.: Was this species analysed in Werner et al. 2014? We thank all data contributors for their assistance in compiling this database, and for their permission to share these data through Dryad. References Soltis, D. E. et al. Chloroplast gene sequence data suggest a single origin of the predisposition for symbiotic nitrogen fixation in angiosperms. Proc. Natl. Acad. Sci. U. S. A. 92, 2647–51 (1995). Werner, G. D. A. et al. A single evolutionary innovation drives the deep evolution of symbiotic N2-fixation in angiosperms. Nat Commun. In Press. (2014). Data References TRY: Cornelissen: Cornelissen, J. et al. Functional traits of woody plants: correspondence of species rankings between field adults and laboratory-grown seedlings? J. Veg. Sci. 14, 311–322 (2003). Cornelissen, J. An experimental comparison of leaf decomposition rates in a wide range of temperate plant species and types. J. Ecol. 84, 573–582 (1996). Cornelissen, J. H. C. et al. Leaf digestibility and litter decomposability are related in a wide range of subarctic plant species and types. Funct. Ecol. 18, 779–786 (2004). Cornwell: Preston, K. a, Cornwell, W. K. & Denoyer, J. L. Wood density and vessel traits as distinct correlates of ecological strategy in 51 California coast range angiosperms. New Phytol. 170, 807–18 (2006). Cornwell, W. K., Schwilk, L. D. W. & Ackerly, D. D. A trait-based test for habitat filtering: convex hull volume. Ecology 87, 1465–71 (2006). Cornwell, W. K. et al. Plant species traits are the predominant control on litter decomposition rates within biomes worldwide. Ecol. Lett. 11, 1065–71 (2008). Ackerly, D. D. & Cornwell, W. K. A trait-based approach to community assembly: partitioning of species trait values into within- and among-community components. Ecol. Lett. 10, 135–45 (2007). Cornwell, W. K. & Ackerly, D. D. Community assembly and shifts in plant trait distributions across an environmental gradient in coastal California. Ecol. Monogr. 79, 109–126 (2009). Craine: Craine, J. M. et al. Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability. New Phytol. 183, 980–92 (2009). Kattge: Kattge, J., Knorr, W., Raddatz, T. & Wirth, C. Quantifying photosynthetic capacity and its relationship to leaf nitrogen content for global-scale terrestrial biosphere models. Glob. Chang. Biol. 15, 976–991 (2009). Laughlin: Laughlin, D. C., Leppert, J. J., Moore, M. M. & Sieg, C. H. A multi-trait test of the leaf-height-seed plant strategy scheme with 133 species from a pine forest flora. Funct. Ecol. 24, 493–501 (2010). Poorter: Unpublished Reich: Reich, P. B. et al. Scaling of respiration to nitrogen in leaves, stems and roots of higher land plants. Ecol. Lett. 11, 793–801 (2008). Reich, P. B., Oleksyn, J. & Wright, I. J. Leaf phosphorus influences the photosynthesis-nitrogen relation: a cross-biome analysis of 314 species. Oecologia 160, 207–12 (2009). Weiher: Weiher, E. in Biological Diversity: Frontiers in Measurement and Assessment. (Magurran, A. E. & McGill, B. J.) 175–193 (Oxford University Press, 2010). Wright: Wright, I. J. et al. The worldwide leaf economics spectrum. Nature 428, 821–7 (2004). Wright, I. J. et al. Irradiance, temperature and rainfall influence leaf dark respiration in woody plants: evidence from comparisons across 20 sites. New Phytol. 169, 309–19 (2006). Manual Literature: De_Faria_2010: De Faria, S. M. et al. Evaluating the nodulation status of leguminous species from the Amazonian forest of Brazil. J. Exp. Bot. 61, 3119–27 (2010). Roggy_1999: Roggy, J. C. et al. Leaf natural 15N abundance and total N concentration as potential indicators of plant N nutrition in legumes and pioneer species in a rain forest of French Guiana. Oecologia 120, 171–182 (1999). Pons_2007: Pons, T. L., Perreijn, K., Kessel, C. Van & Werger, M. J. A. Symbiotic nitrogen fixation in a tropical rainforest: N natural abundance measurements supported by experimental isotopic enrichment. New Phytol. 173, 154–167 (2007). Frioni_2001: Frioni, L., Dodera, R., Malates, D. & Irigoyen, I. An assessment of nitrogen fixation capability of leguminous trees in Uruguay. Appl. Soil Ecol. 7, 271–279 (1998). Freitas_2010: Freitas, A. D. S., Sampaio, E. V. S. B., Santos, C. E. R. S. & Fernandes, A. R. Biological nitrogen fixation in tree legumes of the Brazilian semi-arid caatinga. J. Arid Environ. 74, 344–349 (2010). Gehring_2003: Gehring, C. The Role of Biological Nitrogen Fixation in Secondary and Primary Forests of Central Amazonia. 170 (Cuvillier Verlag, 2003). Becking_1975: Becking, J. Root nodules in non-legumes. In: Torrey, J. G., Clarkson, D. T. The development and function of roots. 507–566 (1975). Soudzilovskaia_2012: Soudzilovskaia, N. A. et al. Legumes affect alpine tundra community composition via multiple biotic interactions. Ecosphere 3, 1–16 (2012). Swensen_1996: Swensen, S. M. The Evolution of Actinorhizal Symbioses: Evidence for Multiple Origins of the Symbiotic Association. Am. J. Bot. 83, 1503–1512 (1996). Markham_2009: Markham, J. H. Does Dryas integrifolia fix nitrogen? Botany 87, 1106–1109 (2009). Rodriguez-Barrueco_1969: Rodriguez-Barrueco, C. The occurence of nitrogen-fixing root nodules on non-leguminous plants. Bot. J. Linn. Soc. 62, 77–84 (1969). Uemura_1971: Uemura, S. Non-Leguminous Root Nodules in Japan. Plant Soil 35, 349–360 (1971). Sprent: Sprent_2001: Sprent, J. I. Nodulation in Legumes. 156 (Kew Publishing, 2001). Sprent_2009: Sprent, J. I. Legume Nodulation: A Global Perspective. (Wiley-Blackwell, 2009). Grin: Grin: USDA. Germplasm Resources Information Network - (GRIN) [Online Database]. National Germplasm Resources Laboratory, Beltsville, Maryland URL at , 2011