Altitudinal variation in body size and resistance to stress in Drosophila melanogaster and D. simulans (Diptera: Drosophilidae) in southern Turkey

Tolerance of cold and heat and body size are traits that are important in thermal selection. Latitudinal and altitudinal transects include environments that gradually change in temperature. However, while there are studies on the effects on body size and cold tolerance in natural populations sampled mostly along latitudinal transects, there are few such studies along altitudinal transects. Resistance to starvation and desiccation, which are also thought to be affected by temperature, are the focus of studies on clines. In this study, we measured the variation in tolerance of cold (chill coma recovery time), body size, resistance to starvation and desiccation in isofemale lines of Drosophila melanogaster and D. simulans that originated from four locations (50 m - 1500 m) along an altitudinal transect in the southern part of Turkey. This revealed clines in the tolerance of cold and body size along the altitudinal transect with some degree of difference between these two species, whereas there were no clines in resistance to starvation and desiccation. This study revealed some differences and similarities between the sibling species D. melanogaster and D. simulans.