Implying quantitative ecology of Drosophilid fauna as a tool for biodiversity assessment - A case study along an altitudinal transect in the Garhwal region of Central Himalaya

Very few studies to date have exploited Drosophilids as potential bio-indicators of biodiversity or ecological integrity. Here we investigate the Drosophila assemblage as a bioindication system especially for the management of tropical areas with high rates of habitat destruction and biodiversity loss. Several sampling surveys were carried out for more than a year along an altitudinal gradient at six stations in the Garhwal region to provide information about the composition of the drosophilid community. Various diversity indices, constancy method and cluster analysis were used to analyse species occurrence. The ecological indices showed a possible positive association between species abundance and environmental heterogeneity of the studied areas. Mandal (1600 m asl) being a transition area between sub-tropical and temperate zones, with a high degree of heterogeneity in climate and vegetation, proved to be most diverse of all stations studied. Consistent with the fact that the corridor from Mandal via Kanchula-Kharak upto Chopta is already advocated as a protected zone, our study proposes usage of drosophilid assemblage composition as a very efficient and accurate tool for future selection and design of protected areas in the region.