Genetic diversity of nine natural Tectona grandis L.f. populations of the Western Ghats in Southern India

Abstract

Teak (Tectona grandis L.f.) is one of the most durable timbers in the world that is used for all conceivable purposes. Its widespread use has constrained the distribution of species to small and isolated populations. The genetic structure within and between nine natural teak growing forests of the Western Ghats of India belonging to the states of Kerala, Karnataka and Tamil Nadu was investigated using amplified fragment length polymorphism markers to provide reasoned scientific management practices and conservation measures. The use of ten selective primer combinations on 180 samples (9 populations X 20 trees) resulted in a total of 665 bands of which 99.4 % were polymorphic. Gene diversity index (H) varied from 0.1387 (Barchi) to 0.2449 (Wayanad). The mean gene diversity (HS) was 0.1995 and the total gene diversity (HT) was 0.264. The Southern Western Ghats populations showed higher within population gene diversity. The relative magnitude of genetic differentiation among populations (GST) was 0.244. Positive correlation between genetic and geographical distances was observed. PCoA, UPGMA and STRUCTURE analyses revealed the tendency of the individual trees within a population to align together indicating specific identity of each population. In the UPGMA dendrogram, Nilambur population joined separately with a large cluster in which the other Kerala populations and Tamil Nadu population formed sub clusters indicating a separate identity for Nilambur population among Southern Western Ghats populations.