Table 3.

Environmental layers considered and used in modeling patterns of South American distribution of Salvator merianae (Argentine black and white tegu), Salvator rufescens (red tegu), Tupinambis teguixin (gold tegus), and these species combined. All data were 30 arc-second resolution.

Variable	Units	Justification	Source
Annual mean temperature (BIO1)	°C	Distribution limits of squamates are constrained by low temperatures at continental scales60	www.worldclim.org (average of values from 1950–2000)61
Maximum temperature of the warmest month (BIO5)*	°C	Although behavioral thermoregulation allows some avoidance of thermal stress, thermal tolerances are conserved in lizard lineages and influence habitat suitability62–64	www.worldclim.org (average of values from 1950–2000)61
Minimum temperature of the coldest month (BIO6)	°C	As per previous justification	www.worldclim.org (average of values from 1950–2000)61
Mean temperature of the warmest quarter (BIO10)	°C	Temperatures need to be warm enough to permit at least a 7-month activity season, corresponding to seasonal activity period in South America49 and observed activity of a few individuals in Florida40	www.worldclim.org (average of values from 1950–2000)61
Mean temperature of the coldest quarter (BIO11)*	°C	Moderate winter temperatures would permit at least a 7-month activity season, corresponding to seasonal activity period in South America49 and observed activity of a few individuals in Florida40	www.worldclim.org (average of values from 1950–2000)61
Annual precipitation (BIO12)*	mm	Influences ecosystem dynamics and primary productivity	www.worldclim.org (average of values from 1950–2000)61
Moderate Resolution Imaging Spectroradiometer [MODIS] Phenology EVI length of season	Days	Season length should influence resource availability, which in turn influences fitness and survival in many animals including lizards65	www.modis.gsfc.nasa.gov 66
Mean annual potential evapotranspiration (PET)*	mm	Measures amount of water evaporated and transpired if water is not limiting; interacts to influence major vegetation associations at continental scales and is a strong predictor of animal species richness world-wide67	www.nysg.umt.edu/project/mod16 (mean of 2000 to 2009 MOD16 A3 PET dataset)
Solar radiation index (SRI)	No units	Important for ectothermic species to meet their thermoregulatory needs	Keating et al.68; equation 2, pp. 1345, using latitude, slope, and aspect derived from USGS map layers

^*Variables used in the final set of environmental layers.