a) Darwin conjectured that the birds evolved on the island itself There were seed-eating features and other altered beaks arose allowing different types of food eating habits like insectivorous and vegetarian finches This process of evolution of different species in a given geographical area starting from a point and radiating to other areas of (geographical) habitats is called adaptive radiation
| (b) Darwin |
de Vries |
| (i) Minor variation (heritable) cause evolution |
Mutation caused evolution |
| (ii) Variation are small and directional |
Mutation are random and directionless |
| (iii) Evolution is gradual |
Single step large mutation / saltation causes speciation |
