3.2.Correlations between genetic variation and environmental versus geographical factors
The Mantel test showed a significant correlation between genetic distance and environmental distance (r = 0.4871, P = 0.001), but between genetic distance and geographical distance was a non-significant correlation (r = 0.0971, P = 0.028). When geographical factors were controlled, a partial Mantel test also showed isolation by environmental distance (r = 0.4797, P = 0.001). Whereas environmental factors were controlled, we could not detect significant correlations between genetic differentiation and geographical distance (r = 0.0118, P = 0.378). The MMRR analysis indicated that the environment factors had large regression coefficient, whereas the effects of geographic distance were not significant (geographic distance: β = 0.0094, P = 0.1075; environment distance: β = 0.2372, P = 0.0001;Table 3 ).
Table 3. Results of the Mantel test, partial Mantel test and MMRR analyzing the correlation between geographical distances, environmental distances and Nei’s genetic distance based on AFLP data.