Linear models.

Developed to examine if and to what extent habitat specialization (Jaccard index) differs across continuous variables (elevation minimum, elevation maximum, elevation range, leaf size variance) and biogeographic origin. Models test the null hypotheses that (1) the Jaccard index is zero (Intercept = Endemic, Indigenous, Non-native) when controlling for the continuous variable and (2) that there is no relationship (slope = 0) between the Jaccard index and the continuous variable. Bold p values indicate significant differences from the null hypotheses. The minimum elevation and elevation range models had significant slopes; however, only the minimum elevation model explained greater than twenty percent of the variance in the data (R2) with endemic species displaying the steepest slope (Fig 6).