Density-dependent natural selection and trade-offs in life history traits.
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.
Mueller
L D
LD
Department of Ecology and Evolutionary Biology, University of California, Irvine 92717.
Guo
P Z
PZ
Ayala
F J
FJ
D000818:Animals; D005075:Biological Evolution; D003433:Crosses, Genetic; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D004463:Ecology; D005260:Female; D014644:Genetic Variation; D008297:Male; D008957:Models, Genetic; D011158:Population Growth; D012641:Selection, Genetic