PowerPoint presentation Theory of evolution through mutation of Hugo de Vries from the website http://www.yourarticlelibrary.com/mutation/mutation-theory-mutation-theory-of-evolution-by-hugo-de-vries/12255/ I hope that this PowerPoint will help you in understanding Hugo de Vries' theory.

1. http://www.yourarticlelibrary.com/mutati
on/mutation-theory-mutation-theory-of-
evolution-by-hugo-de-vries/12255/
Theory of Evolution through Mutation

2. 1935) was a
Dutch botanist and one of
the first geneticists. He is
known chiefly for
suggesting the concept
of genes, rediscovering the
laws of heredity in the
1890s while unaware
of Gregor Mendel's work,
for introducing the term
"mutation", and for
developing a mutation
theory of evolution.

3. According to him, new species are
not formed by continuous variations
but by sudden appearance of
variations, which he named as
mutations. Hugo de Vries stated that
mutations are heritable and persist in
successive generations.

5. Experiments Conducted by Hugo de
Vries:
He conducted his experiments on Evening Primrose
(scientific name is Oenothera Lamarckian), and
found several unusual types. When O. Lamarckian
was self-pollinated and its seeds were allowed to
grow, majority of pollinated plants were similar to the
parents, but a few were different plants.
The different plants were also self-pollinated and
when their seeds were sown, the majority of the
plants were similar to the parents while a few were
still more different plants and this continued
generation after generation. These plants appeared
to be new species, Hugo de Vries suggested from
his experiments that new types of inherited
characteristics may appear suddenly without any
previous indication of their presence in the race.

7. O. Lamarckian

8. Prominent features of the Mutation
Theory1. Mutations or discontinuous variations
are the raw material of evolution.
2. Mutations appear all of a sudden. They
become operational immediately.
3. Unlike Darwin’s continuous variations or
fluctuations, mutations do not revolve
around the mean or normal character of
the species.
4. The same type of mutations can appear
in a number of individuals of a species.
5. All mutations are inheritable.

9. directions.
7. Useful mutations are selected by nature.
Deadly mutations are eliminated.
However, useless and less harmful
ones can persist in the offspring.
8. Buildup of differences produce new
species. Sometimes a new species is
produced from a single mutation.
9. Evolution is a bumpy and discontinuous
process.

10. Points in favor of the Mutation
Theory
1. Mutations are actually the source of all
variations and hence fountain head of
evolution.
2. Mutation theory can explain both
progressive and retrogressive (causing
a return to an earlier and usually worse
state) evolution.
3. As the ratio of mutations is not the
same in all individuals and their parts,
mutation theory can explain the
occurrence of both changed and
unchanged forms.
4. A number of mutations have appeared
in the past.

11. They have given rise to new
varieties.
a) Ancon Sheep is a short legged variety
which appeared suddenly in
Massachusetts in 1791.

12. homed cattle in 1889.
c.) Single mutation can give rise to a new
variety and
even species of plants, e.g., Delicious
Apple, Cicer
gigas, Noval Orange, Red Sunflower.
d.) Hairless cats and double toed cats have
developed
through mutations.

13. Criticism of the Mutation Theory
1. Oenothera lamarckiana of Hugo de Vries
was not a normal plant but a complex
heterozygous (having the two alleles at
corresponding loci on homologous
chromosomes different for one or more
loci) form with chromosome irregularities.
2. Natural mutations are not common
as Hugo de Vries thought them to occur.
3. Most of the mutations are negative or
retrogressive.
4. Mutations are generally recessive while
traits taking part in evolution are usually
dominant.

14. 5. Mutation theory cannot satisfactorily
explain the
development of mimicry, mutual
dependence of
flowers and pollinating insects.
6. This theory does not explain the role of
nature.