Altitudinal variation in lifespan of Drosophila melanogaster populations from the Firtina Valley, northeastern Turkey

Studies of altitudinal changes in phenotype and genotype can complement studies of latitudinal patterns and provide evidence of natural selection in response to climatic factors. In Drosophila melanogaster, latitudinal variation in phenotype and genotype has been well studied, but altitudinal patterns have rarely been investigated. We studied populations from six different altitudes varying between 35 m and 2173 m in the Firtina Valley in northeastern part of Turkey to evaluate clinal trends in lifespan under experimental conditions. Lifespan in the D. melanogaster populations was examined in relation to altitude, sex, temperature (25 °C and 29 °C), and dietary yeast concentration (5 g/L and 25 g/L). As expected high temperature decrease lifespan in all populations. However, it was shown that lifespan was slightly affected by dietary stress. We found that lifespan decreases significantly under thermal stress conditions with increasing altitude. Moreover, there was a slightly negative relationship between altitude and lifespan, which was closely associated with climatic factors such as temperature and precipitation, may suggest local adaptation to climate.