Supporting Information

Forrestel et al. 10.1073/pnas.1612909114

Fig. S1. Regional clade richness, using GPWG (39) as a backbone tree and grafting on the species for each clade, size of clades represent proportion of total richness of that clade.

Forrestel et al. www.pnas.org/cgi/content/short/1612909114 1of3 Fig. S2. Ordination (principal components analysis) of environmental variables (Table S1) from all sites included in study. Site codes are provided in Table S1. Enivronmental variable abbreviations: AP, annual precipitation; C, soil percent carbon; CommRich, total community richness; Fire, estimated fire frequency; GrassRich, grass community richness; GSP, growing season precipitation; GST, growing season temperature; MAP, mean annual precipitation; MAT, mean annual temperature; N, soil percent nitrogen.

Fig. S3. Linear mixed model of grass vs. total ANPP at NA (Left) and SA (Right) sites.

Forrestel et al. www.pnas.org/cgi/content/short/1612909114 2of3 Height Leaf area SLA LDMC Leaf % N Stom. length Stom. density SPI

North America Digitaria monodactyla South Africa Digitaria eriantha Alloteropsis semialata Both Panicum ecklonii Panicum oligosanthes Paniceae Setaria sp Setaria pumila Setaria sphacelata Elionurus muticus Monocymbium ceresiiforme Tripsacum dactyloides Trachypogon spicatus Cymbopogon pospischilii Cymbopogon excavatus Sorghastrum nutans Diheteropogon amplectens Andropogoneae Hyparrhenia hirta Andropogon gerardii Andropogon appendiculatus Schizachyrium scoparium Themeda triandra Heteropogon contortus leucothrix Tristachyideae Eragrostis lehmanniana Eragrostis obtusa Eragrostis minor Eragrostideae Eragrostis curvula Eragrostis bicolor Tragus racemosus Tragus koelerioides Hilaria mutica Hilaria belangeri Bouteloua gracilis Boutleoua barbata Cynodonteae Bouteloua curtipendula Bouteloua eriopoda Bouteloua chondrosioides Bouteloua dactyloides Bouteloua hirsuta Sporobolus fimbriatus Sporobolus heterolepis Sporobolus cryptandrus Zoysieae Sporobolus compositus Aristida ternipes Aristida oligantha Aristida congesta Aristida diffusa Aristidoideae Aristida junciformis Stipagrostis obtusa Stipagrostis plumosa Stipa spartea Pooideae

Fig. S4. Phylogeny of dominant species in NA and SA sites with a subset of trait values mapped onto the tips. Trait values are scaled between zero and one, and larger circles indicate larger values.

Other Supporting Information Files

Table S1 (DOCX) Table S2 (DOCX) Table S3 (DOCX) Table S4 (DOCX) Table S5 (DOCX)

Forrestel et al. www.pnas.org/cgi/content/short/1612909114 3of3