Diversity and distribution of drosophilids (Diptera: Drosophilidae) in the Mandakini Valley of Western Himalaya, Uttarakhand, India: an altitudinal and seasonal study

Uttarakhand is one of the hilly states in the Western-region of Indian Himalaya, home to a vast range of biodiversity. A three-year study (2018–2021) was conducted to assess the drosophilid diversity along an altitudinal gradient and across seasons in the Mandakini valley of the Western Himalayas, Uttarakhand. A total of 37 species of flies belonging to 10 genera were identified, with nine species newly described to science and one as a new record from India. Among the ten genera, <i>Drosophila</i> was predominant with 20 species, followed by <i>Impatiophila</i> with five species, <i>Leucophenga</i> with three species, <i>Liodrosophila</i> and <i>Dichaetophora</i> with two each species, and <i>Lordiphosa, Hirtodrosophila, Mulgravea, Stegana</i> and <i>Zaprionus</i> with one species each. The study showcased a nuanced relationship between elevation and species distribution. As altitude increases, temperature decreases and habitats become increasingly fragmented imposing constraints on the types and abundance of species capable of thriving. Conversely, lower elevation areas exhibited higher population densities but lower species diversity. Additionally, the study unveils the significant impact of seasonal fluctuations on drosophilid population dynamics. The density of drosophilids varied considerably over the seasons (F = 60.56, df = 2, p &lt; 0.001). The distribution of a species or a group of species was uneven in both the temporal and spatial sense.