MOLECULAR PHYLOGENY OF MANGROVES .2. INTRA-SPECIFIC AND INTER-SPECIFIC VARIATION IN AVICENNIA REVEALED BY RAPD AND RFLP MARKERS

Random amplified polymorphic DNA (RAPD) and restriction fragment lengt h polymorphism (RFLP) markers were used to estimate intra-and inter-sp ecific variation in three species of an exclusive mangrove genus, Avic ennia. Intrapopulation polymorphism among the 10 populations of Avicen nia marina, as measured by percentage of polymorphic RAPDs, varied bet ween 17.8 and 38.9%, with a standard deviation of 7.28, and the coeffi cient of variation was 26.5%. Polymorphism in Avicennia officinalis (P ichavaram population, 32.3%) and Avicennia alba (Coringa population, 3 7.8%) was greater than the intrapopulation variation observed in the p opulations of A. marina from each of the respective locations. It was greater than the average percentage of polymorphism at the intrapopula tion level (27.47%) but far less than the variation measured at the in terpopulation level in A. marina. Interpopulation variation in A. mari na (76.7% for RAPDs and 66% for RFLPs) was greater than the variation in any individual population of this species, indicating a high degree of divergence between the populations. Interpopulation variation as r evealed by RAPD and RFLP markers did not indicate the existence of mor e than one distinct entity in this species in India. The implications of these observations in genetic sampling and conservation are discuss ed. Statistical analysis of 109 RAPDs and 84 RFLPs observed in one rep resentative genotype from each species showed that the widely distribu ted A. marina was more closely related to A. alba (genetic distance (1 - F) = 0.22) than to A. officinalis (genetic distance (1 - F) = 0.37) . RAPD analysis of six randomly selected genotypes in each species and principal component analysis of the data also favoured this observati on.