INTRODUCTION: The role of syngameons in adaption to microgeographical environmental heterogeneity is important and could be one of the sources of rich species diversity in tropical forests. In addition, negative frequency- or density-dependent selection is one of the major processes contributing to the maintenance of genetic diversity. METHODS: To assess genetic factors that affect the fitness of seedlings of RESULTS: A Bayesian based clustering analysis revealed that three genetically distinct clusters were observed in almost all populations throughout the distributional range of the species in Malay Peninsula and provided the optimum explanation for the genetic structure of 182 mature individuals in the plots. The two clusters showed larger genetic differentiation from the ancestral admixture population, but the other one was not differentiated. The bi-parental larger genetic heterogeneity was associated with a significantly higher probability of seedling survivorship, and likewise, higher performance of vertical growth of the seedlings
but the seed weight and genetic relatedness did not significantly affect those. DISCUSSION: This evidence suggests that fitter seedlings derived from mating between parents with different genetic clusters contribute to maintaining genetic diversity through negative frequency-dependent selection and may have an important role in adaptation in the tropical forest plant community.