Population density, genetic diversity and hot spots of Commiphora wightii (Arnott) Bhandari in Rajasthan State

Abstract

Commiphora wightii (Arnott) Bhandari also known as ‘Guggal’, is a critically endangered medicinal plant species. Natural population of this species is declining due to poor regeneration, over-exploitation and destructive harvesting methods. In present study extensive surveys were conducted in all the guggal occurring forest areas of Rajasthan state with the objectives to study the population density, genetic diversity and its relationship with geographical patterns, distances and agroclimatic zones. Average population density of guggal was 21.9 plants ha−1 in guggal occurrence areas of forests in Rajasthan. The highest density (105.9 plants ha−1) was recorded in Sawai Madhopur and lowest (1.6 plants ha−1) in Jhalawar district. Variation in guggal population density was also observed due to altitude differences. The maximum density (40 plants ha−1) was recorded in altitude range from 301−350 m AMSL mainly in Aravalli range and it reduces at higher (>350 m AMSL) and lower (<301 m AMSL) altitudes.Genetic diversity was studied with 96 genotypes collected from all over Rajasthan using selected six RAPD primers. The genetic distances among these genotypes ranged from 0.000 to 0.732. Statistical analysis indicated low genetic diversity (H = 0.195; I = 0.299), low genetic differentiation (GST = 0.169) and moderate gene flow (Nm = 2.455) between four agroclimatic zone populations. These results indicate that these populations are in process of genetic drift and genetic differentiation. The Mantel test showed statistically significant correlation (R = 0.306; p = 0.000) between pairwise geographical distance and genetic distance.