Island Ecosystems Host Rich Diversity in Coconut (Cocos nucifera): Evidences from Minicoy Island, India

Abstract

Oceanic island ecosystems present immense opportunities for the study of species evolution due to their isolated geographical nature and presence of highly rich species diversity. Assessment of genetic diversity and population structure of four distinct coconut groups, viz. Giant, Ordinary, Micro and Mini Micro types of Minicoy Island, India, was carried out using morphological traits and microsatellite markers. The morphological data set, analysed using principal component analysis, revealed high genetic variability for fruit component traits. The occurrence of Laccadive Mini Micro Tall palms, bearing the smallest coconuts in the world, was observed in the island. The nuts of these palms had a low copra content of 5 g/nut, but high oil content of around 73%. A total of 70 alleles were detected among the four distinct coconut groups of the Island using 19 polymorphic microsatellite markers with a mean of 3.68 alleles per locus. The fixation index ranged from 0.153 to 0.424 indicating highly variable levels of inbreeding in these populations. Pair-wise population matrix formed by Nei’s genetic identity showed that Laccadive Mini Micro Tall was genetically distinct from all other groups. The study revealed the presence of rich coconut diversity in islands and highlights the importance of exploration and conservation of such diverse accessions with rare genes for utilizing them in crop improvement.