Investigation of seasonality of reaction norms for preadult life history traits in Drosophila melanogaster

Adaptation ability to varying environmental conditions, makes the organism able to survive. Drosophila melanogaster is a species originated from Africa and spread all around the world. It can live in a wide range of habitats through its high adaptability to new environments. Besides its global distribution, Drosophila melanogaster shows seasonal adaptations to the local climate. Temperature, as an environmental factor, is the most important component of seasonality that affects the biological processes and has a major effect on ectotherms' physiology and fitness. As stated in life history theory, adaptive changes are shaped both by the organisms' genotype and the responses to the environmental changes. Likewise, seasonal changes in temperature determine the survival limits of organisms and also triggers the evolution of the life history traits. In addition to adaptive traits, organisms react to environmental changes with the phenotypic plasticity and increase their survival. In this thesis, full-sib inbred lines, which were collected in different timepoints of the years in 2014, 2015 and 2016 from Yeşilöz, Ankara and inbreeded for 20 generations, are studied for developmental time and viability in thermal reaction norms, in order to investigate the seasonality of the traits. Additionally, the correlation between these characters and climatic variables that change between seasons and years were investigated. According to the results, viability, developmental time, and developmental time reaction norms did not show seasonality. Furthermore, the correlation between climatic parameters and characters showed a significant correlation between pupa to adult developmental time and maximum precipitation when tested at 18°C. In sum, we suggest that the seasonality did not affect pre-adult life history traits on Yeşilöz population, and our results suggest that these traits are not under seasonal selective pressures.