2. Hugo De Vries was born in Netherlands in 1848
He worked as a professor of plant physiology
De Vries proposed the mutation theory of evolution in1901
He stated that mutation is the universal source of origin of species
Mutation is sudden changes occurring in the genetic material
De Vries postulated the mutation Theory based on his observation on an ornamental plant called
evening primrose Oenothera lamarkiana. this is wild plant.
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3. De Vries reared these three verities in his garden.
He raised about 54343 plants in a period of 8 years. Among these plants he found 837 plants new varieties
and where different from O. lamarckiana.
He proved that these new varieties bred true.
The new varieties were produced by a sudden changes in the wild varieties
He classified these new varieties into four
1) Progressive Species
2) Retrogressive Species
3) Degressive Species
4) Inconstant Species
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4. Progressive Species
In this case, one or more new characters are observed which are quit different from the original
plant.
O. gigas is more vigorous than the parents plant and much stouter with large leaves and
flowers.
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5. Retrogressive Species
When in mutant there is loss of one or more characters of the parental nature.
O.Nanella is a dwarf pant having only one fourth of the height of parental plant.
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6. Degressive Species
One or more essential charecters are lost and due to this their survival become limited.
In O. albida, the chlorophyll becomes defective hence could not survive.
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7. Inconstant Species
These are the mutant which behave just like the parents and occasionally give rise to mutant.
In O.lata bears only pistals in the flowers and hence self pollination is not possible.
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8. Mutation: Mutation is a sudden changes of a gene or chromosome from one form to
another.it produces an alternation in the character under the control.
Classification of mutation:
1. Somatic mutation
2. Germinal mutation
3. Gametic mutation
4. Zygotic mutation
5. Dominant mutation
6. Recessive Mutation
7. Back mutation
8. Lethal Mutation
9. Spontaneous Mutation
10. Induced Mutation
11. Macromutation
12. Micro mutation
13. Gene Mutation
14. Chromosomal Mutation
15. Biochemical Mutation:
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9. Gene Mutation:
Molecular basis of gene mutation
1. Insertion
2. Deletion
3. Inversion
4. Substitution
A) Transversion
B) Transition
5. Frame-shift Mutation
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