Genetic differentiation in Thai populations of the rare species Afgekia sericea Craib (Leguminosae) revealed by RAPD-PCR assays

Genetic diversity within and among populations was investigated using RAPD- PCR assays in a rare species, Afgekia sericea Craib. Two hundred and sixty- nine individuals were sampled from nine geographically isolated populations from northeastern Thailand. This study includes 73 RAPD markers. Within po pulation polymorphism as measured by percentage of polymorphic RAPDs, varie d between 38.4% and 60.3%. Genetic variability was measured using Shannon's information index and partitioned into between- and within-population comp onents. Overall, genetic variation among A. sericea populations was high (H -sp-H-pop)/H-sp=48.2%. The genetic diversity for the species (H-sp) was 43. 2%. Mean of within- population values (H-pop) for all populations was 0.224 . The total genetic diversity was explained by high variation among populat ions (mean Gst=0.426), which is consistent with low gene flow among populat ions (Nm=0.35). High between-population genetic variation observed in this study could be explained by limited migration through seed and/or pollen di spersal among populations. Conservation strategies of A. sericea are discus sed in the context of these results.