2.2 Environmental factors
For the extraction of environmental variables (i.e., elevation, mean
annual temperature, temperature seasonality, mean annual precipitation,
precipitation seasonality, net primary productivity) for each population
of lizards, we used the Raster package in R (Hijmans and Etten,
2012). We elected to use the annual mean temperature and precipitation
because these climate variables represent the mean yearly climate
conditions that can influence some life-history traits of lizards across
populations (Volynchik, 2014; Anderson et al., 2022). Thus, tested for a
relationship between body size variation across populations of female
lizards and these climatic variables (Volynchik, 2014; Deme et al.,
2022a). Furthermore, temperature seasonality and precipitation
seasonality were used because these variables represent the annual
variation in climate conditions, with lower annual variability
indicating more stable climates and greater active time for scouting for
resources (Meiri et al., 2013; Meiri et al., 2020). To extract these
environmental factors, we used the highest resolution within a 2.5 arc
minute resolution grid (1 × 1 km) from the Worldclim2.1 database
(http://www.worldclim.org; accessed on 30 August 2021). For the
net primary productivity, we extracted data using the highest resolution
within 2.5 arc minutes from the Earth’s land surface areas
(http://chelsa-climate.org/; accessed on 2 January 2022). Finally,
our extracted environmental (climate) variables were set at WGS 1984 and
projected to UTM Zone 20N geographic spatial reference.