Selection for resistance to desiccation in Drosophila simulans

Selection for resistance to desiccation was carried out for 15 generations in two lines of Drosophila simulans from a genetically heterogeneous base population. Realized heritabilities in the two lines were 0.11 and 0.09 for females, and 0.19 and 0.11 for males. The F1 and F2 progenies from crosses among selected and control lines were tested individually for latency to immobilization in a desiccating environment; the distributions of these latencies suggest polygenic differences between the selected and control lines with proportionate representation of sex-linked effects. Desiccation resistance, which was greater in females than in males, decreased with age. Estimates of water content before and after partial desiccation suggest that the basis of greater desiccation resistance in the selected lines, and in females relative to males, was a lower rate of water loss, perhaps owing to increased spiracular control.