Table 2: The relative contribution (%) of geographic and
environmental predictor variables to Speyeria atlantis , northernS. hesperis , and southern S. hesperis ecological niche
models (ENMs). Geographic predictor variables included terrain
ruggedness, heat load (based on terrain slope and aspect), and land
cover (12 categories). Environmental predictor variables included mean
temperature of the coldest month, mean temperature of the warmest month,
the difference between mean temperatures of the coldest and warmest
months (continentality), degree-days below 0°C (chilling degree days),
degree-days above 5°C (growing degree days), extreme minimum
temperature, precipitation as snow, and summer (Jun to Aug)
precipitation. Relative contribution was measured as the drop in AUC
values after each variable was randomly permuted. For each of the three
lineages, five ENMs were built, each withholding a different 20% of
occurrence localities used for model evaluation. The mean and standard
deviation (s.e.) of relative contributions for each predictor variable
across the five ENMs are reported.