Genetic variation in island and mainland populations of Ficus pumila (Moraceae) in eastern Zhejiang of China

Genetic variation, which is a prerequisite for the evolutionary response to environmental changes, may influence the long-term persistence of populations. Using six microsatellite markers, we investigated the genetic structure of island and mainland populations of Ficus pumila from the Zhoushan archipelago and the nearby eastern China mainland. The number of alleles per locus ranged from 2 to 4 with an average of 3.2. Several populations showed a significant bias from the Hardy-Weinberg equilibrium, mostly due to heterozygote deficit as indicated by positive inbreeding coefficients. The Mean of the number of alleles per locus, the allelic richness, the observed and the expected heterozygosities were 2.98, 2.94, 0.34 and 0.43, respectively. The overall genetic differentiation was 0.075. The island populations had comparable within-population diversity to the mainland populations. Genetic differentiation among the mainland populations (0.047) was about one half of that of the island populations (0.081), which was attributed to one island population. When this population was excluded, the island populations had the same F_ST as the mainland populations. High gene flow in Ficus pumila may explain the similar genetic variation found in the island and mainland populations.