Selection Landscape

a graphic model of evolution in the form of map.

The term “selection landscape” and the model itself were proposed by the American biologist S. Wright in 1931. On the model, the horizontals represent the states of the genotypes and, consequently, of the phenotypes possible in the given environment. Elevations in the landscape express greater adaptability; valleys and depressions, lesser. Evolution is represented as a movement of a population from one adaptive peak to another, usually higher, peak. For example, with an increase in variability and a decrease in elimination, a population begins to occupy not only the very peak but also the slopes of an adaptive hill; when this happens, some of the population may appear in the foothills or lower slopes of a different adaptive peak. The population under the influence of selection will then inevitably begin to ascend the new adaptive elevation until it reaches the peak. By using the selection landscape, it is possible to create models of changes in the environment, the role of gene drift, the significance of the degree of isolation, and other factors that determine the direction of selection and its intensity.