Mutationism

a biological concept that regards evolution as a discontinuous process resulting from major isolated hereditary changes.

According to mutationism, changes called macromutations, or saltations, arise in individuals of an original species and immediately create new life forms which, if environmental factors are favorable, become the progenitors of new species. Mutationism considers evolution to be the result of an.internal factor, hereditary change. The theory thus denies that external factors such as natural selection are the motivating force behind evolution. Natural selection is treated as a factor that limits the variety of life forms by eliminating species that are incompatible with the environment. Mutationism is close in this respect to autogenesis. It differs from autogenesis in that it does not view evolution as a continuous process.

Mutationism is not a single theory. Alternate views of evolution have been espoused by several researchers. H. De Vries, who formulated the mutation theory of evolution, was the original proponent of mutationism. Views similar to mutationism underlie the theory of preadaptation, advanced by the French biologist L. Cuénot; the theory of saltation, advanced by the German biologist R. Goldschmidt; and some other less familiar theories.