Title: Climate change & range expansion in Drosophilids

Abstract

During the last century, the earth's average temperature has increased by 0.3 to 0.6 °C. This increased temperature has resulted in the reorganization of fauna. In environments with varying temperatures, phenotypic values must be adjusted to meet environmental demands. In ectothermic Drosophilids, thermal selection is a very significant factor affecting phenotypes (i.e., genetic effects) as well as induced effects on phenotypes (i.e., plastic effects). According to climate data for the last fifty years, average temperatures in the Western Himalayas have changed significantly, impacting Drosophilid distribution and boundaries. The distribution of D. nepalensis in lower ranges has significantly declined; however, D. ananassae has been introduced to lower to mid mountainous ranges. Comparing fecundity, hatchability, and viability at different growth temperatures also revealed that the traits showed significant decreases at 17 °C in D. ananassae and at 25 °C in D. nepalensis. Hence, these recent range changes for these two species are genetically influenced by ecophysiological and plasticity-influenced by life history traits. The results of our research indicate that thermal plasticity can be species-specific and that climate change might cause such traits to not match the changing environment. As indicators of habitat changes due to changing climatic conditions, D. nepalensis and D. ananassae can be considered. Biologists who study the evolution of life can offer unique insight into the effects of climate change on earth's biodiversity.