Trade-off between r -selection and K -selection in Drosophila populations

Abstract
Density-dependent genetic evolution was tested in experimental populations of D. melanogaster subject for 8 generations to natural selection under high (K-selection) or low (r-selection) population density regimes. The test consisted of determining at high and at low densities the per capita rate of population growth of the selected populations. At high densities, the K-selected populations showed a higher per capita rate of population growth than did the r-selected populations, but the reverse was true at low densities. These results corroborate the predictions derived from formal models of density-dependent selection. No evidence of a trade-off in per capita rate of growth was observed in 25 populations of D. melanogaster, each homozygous for a different 2nd chromosome sampled from a natural population.