Present the views regarding the origin of variation and speciation.

(N/A) Mendel had mentioned about heritable factors influencing phenotype. Darwin either ignored these observations or kept silent about them. In the first decade of the $20^{th}$ century,Hugo de Vries,based on his work on the evening primrose,brought forth the idea of mutations—large differences arising suddenly in a population.
He believed that it is mutation which causes evolution and not the minor variations (heritable) that Darwin talked about. Mutations are random and directionless,while Darwinian variations are small and directional. Evolution for Darwin was a gradual process,whereas according to de Vries,mutation is the cause of speciation and he termed it as $Saltation$ (single-step large mutation).