Genetic Analysis of Natural Populations of DROSOPHILA MELANOGASTER in Japan. II. the Measurement of Fitness and Fitness Components in Homozygous Lines.

Fifty lethal-free, sterility-free isogenic lines of Drosophila melanogaster that were randomly sampled from a natural population were tested for net fitness and other components of fitness by competition with D. hydei. Larval viability and developmental time were also measured using the balanced marker method. Distribution patterns of these fitness components were similar, but correlation between the fitness components varied depending on the combinations used. The highest correlations were obtained between net fitness and productivity (r(p) = 0.6987, r(g) = 0.9269). The correlation between net fitness and total larval viability was much lower (r(p) = 0.1473 and r(g) = 0.2171). These results indicate that measuring net fitness, not just a component of fitness, is necessary for the good understanding of the genetic structures of natural populations.