Fig. 3
Cold tolerance, morphological traits (body colour and body size) and environmental conditions. The best-fit models are presented in tables. Relationship between latitude (as a proxy of photoperiod) and PC2 (as a proxy of latitudinally varying temperature) and A chill coma temperature (CTmin), B chill coma recovery time (CCRT), C fly body colour (measured as colour intensity) and D fly body size (measured as weight) in D. flavomontana (D. fla) and D. montana (D. mon) populations. The effects of local climatic conditions (PC1; see Fig. 2) on the western coast and in the Rocky Mountains are illustrated in grey scale (lighter colours represent the western coast populations and darker ones the Rocky Mountains populations). Error bars represent bootstrapped 95% confidence intervals (Mean ± CI). Significant regression lines for latitude or PC2 with standard errors are shown. Significance levels were obtained from GLMMs or LMM: NS non-significant, *P < 0.05, **P < 0.01 and ***P < 0.001