Theory of evolution Darwin vs Hugo de Vries

   
What is the origin of this variation and how does speciation occur?




  • Even though Mendel had talked of inheritable 'factors' influencing phenotype, Darwin either ignored these observations or kept silence. 
  • In the first decade of twentieth century, Hugo deVries based on his work on evening primrose (Oenothera lamarkiana) brought forth the idea of mutations – large difference 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 gradual while deVries believed mutation caused speciation and hence called it saltation (single step large mutation). 
  • Studies in population genetics, later, brought out some clarity.
Theory of evolution Darwin vs Hugo de Vries
Charles Darwin
Hugo de Vries
Branching descent and natural selection are the two key concepts of Darwinian Theory of Evolution

Small and directional

Nature selects for fitness

there must be a genetic basis for getting selected and to evolve

Adaptive ability is inherited.

It is slow and gradual
He believed that it is mutation which causes evolution and not the minor variations (heritable)

Mutations are random and directionless.

deVries believed mutation caused speciation and hence called it saltation

deVries believed mutation caused speciation and hence called it saltation

saltation  (single step large mutation)


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