A COMPLEX ADAPTIVE SYNDROME IN DROSOPHILA CAUSED BY MICROCLIMATIC CONTRASTS

Temperature and humidity are among the most important environmental fa ctors affecting insect adaptive strategies and evolution. Here, we rep ort multiple adaptive differences between Drosophila melanogaster isof emale lines derived from the opposite slopes of Lower Nahal Oren canyo n at Mount Carmel, Israel. The slopes are separated by 100 m at the bo ttom and 400 m at the top, and contrast sharply in physical and biotic factors. The multivariate fitness complex analysed in D. melanogaster included oviposition temperature preferences, viability and longevity changes, caused by short-term and lifetime temperature treatments, an d resistance to drought stress at different temperatures. Some of thes e measures were obtained for the sibling species, D. simulans, and gav e results that paralleled those of D. melanogaster. We conclude that s trong microclimatic natural selection overrides migration in Drosophil a at this microsite.