Fig. 5. Structure analysis of Opisopappus taihangensisand Opisopappus longilobus .
a: Total 17 populations divided into OLa, OLb, OTc and OTd groups; b: The populations of OLa group; c: The populations of OLb group; d: The populations of OTc group; e: The populations of OTd group.
The EEMS results (Fig. 6) revealed that a significant migration barrier occurred among populations at the junction of two species along the Taihang Mountains. Interestingly, the migration channel for the individuals of the two species was not along with the mountainous areas but more inclined to the plains in the Taihang Mountains. Additionly, the populations closest to the migration barrier had much higher migration rate than the average of whole species. The areas with the highest genetic diversity tended to be in the areas with low migration rates. Neverthless, the areas with the highest genetic diversity ofO. longilobus was just in the obstacle areas between O. taihangensis and O. longilobus .