Genetic diversity and population structure of Buddleja crispa Bentham in the Himalaya-Hengduan Mountains region revealed by AFLP

• Buddleja crispa is a species with high genetic diversity.
• The populations of B. crispa were divided into two genetic groups.
• Most of higher diversity populations were located in the center of the distribution areas.
• Population differentiations of B. crispa are more influenced by barriers of rivers and mountains than geographic distance.

Buddleja crispa Benth. is one of the most morphologically variable species in genus Buddleja, and it is widely distributed in the Himalaya-Hengduan Mountains (HHM) region. This study used AFLPs as a tool to examine the genetic variation among and within 25 populations of B. crispa. Analysis of population genetics of the species aimed to clarify morphological variation, current distribution patterns, strong adaptability to habitats, and the effects of geological factors in the HHM region. The genetic structure results, based on PCoA and NJ cluster analyses, revealed that the populations of B. crispa were divided into two genetic groups. Furthermore, the peripheral populations had lower genetic diversity than the populations in the center of the distribution areas (Three Parallel Rivers). We conclude that the gene flow (predominantly seed and pollen flow) and the population differentiation of B. crispa might be more affected by the barriers formed by rivers and mountains than by geographic distance.