Genetic and geographic variation of the mangrove tree Bruguiera in Sri Lanka

The variation in two Bruguiera species in populations from different climatic and macrogeographic regions along the western to southeastern coastal area in Sri Lanka was studied using RAPD (Random Amplified Polymorphic DNA), Intra- and interspecific variation was observed using 20 primers of the 45 primers screened. Some primers showed diagnostic banding patterns and allowed unambiguous differentiation between B. sexangula and B. gymnorhiza without any indication of hybrid individuals. RAPD markers were also used to produce a similarity matrix among individuals of a species. A higher degree of polymorphism was observed within populations of B. gymnorhiza in Rekawa, situated in the climatically intermediate (between the wet and dry) zone, than within populations from the wet zone (Galle and Negombo). RAPD data analysis did not reveal a clear relationship between genetic differences and macrogeographical variation along the western and southern coastal area in Sri Lanka, but indicated that a small population of B. sexangula was genetically different. A more pronounced genetic difference at the population level in B. sexangula than in B. gymnorhiza is suggested. (C) 2000 Elsevier Science B.V. All rights reserved.