Abstract
Theories of density-dependent natural selection state that at extreme population densities evolution produces alternative life histories due to trade-offs. The trade-offs are presumed to arise because those genotypes with highest fitness at high population densities will not also have high fitness at low density and vice-versa. These predictions were tested by taking samples from six populations of Drosophila melanogaster kept at low population densities (r-populations) for nearly 200 generations and placing them in crowded cultures (K-populations). After 25 generations in the crowded cultures, the derived K-populations showed growth rate and productivity that at high densities were elevated relative to the controls, but at low density were depressed.
Highlights
We describe an experiment designed to overcome these problems, the results of which confirm that trade-offsdo occur in the evolution by density-dependent natural selection
Density-Dependent Natural Selection and Trade-Offs in Life History Traits populations, both derived from r-populations transferred to the K-environment; the controls are two types of low density populations
The trade-offs were created from samples of each r-popuare presumed to arise because those genotypes with highest fitness at high population lation and had been maintained at high densities will not have high fitness at low density and vice-versa
Summary
Title Density-dependent natural selection and trade-offs in life history traits. Density-Dependent Natural Selection and Trade-Offs in Life History Traits populations (rK- and rx rK-populations), both derived from r-populations transferred to the K-environment; the controls are two types of low density populations The rK-populations densities evolution produces alternative life histories due to trade-offs.
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