Temperature map of the east coast of the USA. The three collection sites for natural D. melanogaster populations are denoted by circles (Jacksonville, FL 30.33 °N, 81.66 °W; Media, PA 40.04 °N, 76.30 °W; Bowdoin, ME 44.03 °N, 73.20 °W). To study sex differences in thermal preference the Media, PA populations were used. Thermal plasticity experiments were performed on Jacksonville, FL and Bowdoin, ME populations only.