Morphological variation in wings of Drosophila species from Assam-Meghalaya rolling terrain

This study investigates seasonal plasticity in wing traits of 16 Drosophila species collected from selected localities of the rolling terrain in the Assam-Meghalaya border region. Field sampling was conducted during pre-monsoon, monsoon, post-monsoon, and winter seasons using fruit-baited traps methods (Hegde et al., 2001). Representative species were identified using morphological keys and confirmed with molecular characterization where required. Wing length, straight vein number, and cross vein number were measured in males and females using digital imaging and landmark-based geometric morphometrics. Results revealed significant seasonal variation in wing traits. Drosophila sechellia showed the largest wings (♂ = 3.93 ± 0.68 μm; ♀ = 3.95 ± 0.69 μm) during the rainy season, likely due to resource abundance, while Drosophila bipectinata exhibited smaller wings (♂ = 1.01 ± 0.10 μm; ♀ = 1.03 ± 0.10 μm) in winter, suggesting adaptation to desiccation and low temperature. Drosophila melanogaster displayed higher plasticity than other species. These findings highlight the influence of seasonal environmental drivers on wing variation and demonstrate the value of wing morphometrics as bio indicators of ecological resilience and climate variability in North-East India.