XVI International Botanical Congess

Acanthus ilicifolius is a small mangrove shrub widely distributed in South China and Hong Kong. We investigated genetic diversity in the species. No polymorphism was found at 21 isozyme loci surveyed. However, both RAPD and ISSR markers revealed substantial variation at the species level (P = 58.8% and 49.3%, respectively). The total gene diversity (Ht) was 0.185 and Shannon's information index (I) was 0.288 based on RAPD data, comparable to the estimates based on ISSR data (Ht = 0.142 and I = 0.218). The extent of genetic differentiation among populations was high (Gst = 0.307 - 0.380), indicating that gene flow was restricted (Nm = 0.407 - 0.564). Genetic and ecological factors are discussed in relation to the species' conservation and management.