Fluctuating asymmetry and fitness in Drosophila melanogaster

Models predict that developmental stability measured by fluctuating asymmet ry should be positively correlated with fitness. Although such a correlatio n has often been suggested by indirect studies, there is still a lack of di rect experimental evidence. In this note, I have measured the fluctuating a symmetry of sternopleural bristle counts in 32 lines of Drosophila melanoga ster sharing the same genetic background but displaying all combinations of five visible mutations. Fluctuating asymmetry was heterogeneous among line s, suggesting a direct impact of the mutations on developmental stability. Two measures of fitness were made for each line: productivity (a combined m easure of fecundity and egg-to-adult survivorship) and competitive male mat ing success. Fluctuating asymmetry was correlated with neither of these two components of fitness. This suggests that generalizations about fluctuatin g asymmetry must be taken with care.