Thermal Adaptation and Stress Resistance in D. subobscura Populations from Two Altitudes at Stara Planina Mountain (Serbia)

Abstract

Climate change and global warming are affecting many insect species in different ways. Organisms develop diverse mechanisms responding to variable environmental conditions. Due to global warming and the rise in mean and extreme temperatures, the importance of an individual’s ability to adapt to temperature stress will further increase. Our focus in this study is the thermal response, which is considered to be one of the crucial elements of individual fitness and survival in a fast changing environment. We investigated stress resistance traits: desiccation and heat knock- down time in two Drospohila subobscura populations from two different altitudes (1080m and 1580m a.s.l.) along Stara planina mountain slopes in Serbia. The F1 progeny of the mass populations from both localities was used to establish six experimental groups at three different temperature regimes: 25⁰C, 19⁰C and 16⁰C. Our aim was to determine whether there is a correlation between altitude/origin of populations and/or laboratory thermal evolution within these resistance traits. Flies from all groups were tested (scored every hour) for desiccation mortality at those temperatures. To score heat knock-down time all groups were placed into vials with moistened cotton plugs to prevent desiccation, kept at 37⁰C for seven hours, and knock down flies were scored every 30 minutes. Our results indicate that the population origin, as well as laboratory thermal evolution have a significant influence on the analysed traits. Individuals originating from the higher altitudes reared at higher temperatures show better resistance to thermal shock.