Genetic Variability for Density Sensitivity of Three Components of Fitness in DROSOPHILA MELANOGASTER.

This study examines natural genetic variation in density sensitivity of three components of fitness in Drosophila melanogaster using the method of chromosome extraction. Different lines are differentially sensitive to density. The distribution of measures of density sensitivity of chromosomal homozygotes is different from that of random chromosomal heterozygotes for both location and dispersion. Density sensitivity of the components is about as variable as any of the fitness components themselves at fixed densities. The consequences of the exact nature of this density dependence are discussed with respect to the stage of the life cycle at which density dependence occurs, and the mathematical form that it takes. There is no evidence of trade-offs among the components or their density sensitivity.