Mutation Theory of Evolution
Definition : According to this theory, evolution is a discontinuous and jerky process, where new species arise from preexisting species in a single generation.
Introduction : Hugo De Vries (Dutch botanist0 suggested the mechanism for variations in species as Mutation Theory.
He worked on the plant, evening primrose – O. Lamarkiang. This plant was allowed to self-pollinate for a number of generation. Thereafter, he observed that many plants of first generationer almost similar to parental type, with minor variations, however, 837 out of 54,343 members were found to be very different in characters like shape, size of flower, size of seeds etc. These markedly different plants were called Primary/Elementary species. A few plants of the second generation were found to be more different from parental type. And finally, a new type much longer than the original type was obtained “O. gigas” (He found chromosomal variations in each generation).
Hence, he concluded that, evolution is a discontinuous and jerky process. And occurs by mutation.
According to Mutation theory, evolution is a discontinuous and jerky process, (which occurs suddenly) in which there is a jump from one species to another. In this respect, new species arise from pre-existing species in a single generation (called saltations)
De Vries, did not explain the method of their origin, (Actually, mutations arise due to changes in the genetic makeup and not by environmental changes, therefore, the so-called new species were actually ‘Varieties’)