Study of genetic variation and phenetic relationships in some vulnerable taxa from Indian sundarbans following RAPD marker analysis

The mangrove ecosystem plays an important role in maintaining coastal ecological balance and is also one of the most highly productive and dynamic ecosystems to mankind, providing food, livelihood and ecological security. The plant species of this ecosystem are constantly under environmental stress due to the highly saline conditions and extreme temperatures. Studying the genetic diversity of mangrove plants is important in taking effective measures to protect these species. The present study, being the first attempt in Indian Sundarbans, deals with RAPD (Random Amplified Polymorphic DNA) marker study of three IUCN declared ‘Vulnerable’ mangrove species viz. Xylocarpus granatum , Xylocarpus mekongensis and Heritiera fomes of Indian Sundarbans to assess its genetic diversity to trace their reduction in population size. These were collected from two distinct populations of Indian Sundarbans i.e. Sajnekhali Tiger Reserve and Bonnie Camp area. It was found that intra-specific polymorphism was highest (80%) in Xylocarpus granatum in and lowest (60 %) in Xylocarpus mekongensis while Heritiera fomes showed moderate (71.42 %) level of polymorphism. The decreasing population size can be assessed through the low genetic variation of Xylocarpus mekongensis and Heritiera fomes rather than Xylocarpus granatum . It can further be said that comparatively high genetic variation of Xylocarpus granatum , though, does not exactly correspond to its population structure, it may be due to its isolated distribution, dissimilar edaphic factors and different anthropogenic activities within the mangroves of Indian Sundarbans. We can conclude that molecular marker study provides an effective tool to access the existing inter- and intra-specific genetic polymorphism within mangrove species of Indian Sundarbans and to explore their conservation strategy.