Isolation Effects and Soil Properties Drive Genetic Differentiation in Ormosia microphylla Populations

Genetic diversity analysis revealed moderate overall genetic diversity of O. microphylla populations, with the ZD showing the highest and the JX the lowest genetic diversity. Compared to the populations outside the tiankeng, the LY, located in a karst tiankeng, exhibited lower genetic diversity. This reduced genetic diversity of LY was possibly influenced by the combined influence of selective pressures unique to the tiankeng environment as well as the founder effect. Genetic structure analysis further indicated that the optimal number of clusters for the six populations was K=7. The LY exhibited a relatively pure genetic constitution, whereas the other populations exhibited more complex genetic structures. Phylogenetic analysis and assessments of genetic differentiation coefficients further demonstrated significant genetic distance of the LY from the other populations, with a high degree of differentiation. Overall, there was a significant level of genetic differentiation among the six populations.