Considering the extent of our M area (i.e., continental),
our A component consisted of coarse-scale climatic and topographic variables.
Specifically, we included 15 “bioclimatic” layers plus elevation, all at
~4.6 km (2.5′) spatial resolution. The climatic data included annual
mean temperature, mean diurnal range of temperature, isothermality,
temperature seasonality, maximum temperature of warmest month,
minimum temperature of coldest month, temperature annual range,
mean temperatures of warmest and coldest quarters, annual precipitation,
precipitation of wettest and driest months, precipitation seasonality,
and precipitation of wettest quarter