How mutation creates genetic variation and selection acts upon these to create novel traits facilitating evolution of characters and speciation of organisms.

1. MUTATIONS: CREATING
VARIABILITY IN
POPULATION
Mechanisms and
consequences
By-
Priyankar Mondal
A discussion for Wednesday Forum

2. ©Priyankar Mondal, M.Sc., Entomology

3. ©Priyankar Mondal, M.Sc., Entomology

4. Why
Variation
is so important ???
©Priyankar Mondal, M.Sc., Entomology

5. Species on Earth occupy well defined places in the
ecosystem which we call “Niches”!
Problem is….
Niches do not have a ‘constant state’, it is
dynamic and changes with environment beyond the
control of the organism which even could eliminate
a group of organism permanently!!
©Priyankar Mondal, M.Sc., Entomology

6. ©Priyankar Mondal, M.Sc., Entomology

7. ©Priyankar Mondal, M.Sc., Entomology

8. ©Priyankar Mondal, M.Sc., Entomology

9. ©Priyankar Mondal, M.Sc., Entomology

10. ©Priyankar Mondal, M.Sc., Entomology

11. ©Priyankar Mondal, M.Sc., Entomology

13. Genetic variation
Environmental variation
Genotype-by- Environment
interaction variation
©Priyankar Mondal, M.Sc., Entomology

14. Daphnia pulex
After sensing the
kairomone from
Phantom midge larava
ENVIRONME
NTAL
VARIATION
environments can influence
phenotype is by altering
gene©Priyankar Mondal, M.Sc., Entomology

15. When populations harbor genetic
variation
for environmental sensitivity
Phenotypic plasticity

16. Genetic variation
how it is introduced….
how it affects the population….!
©Priyankar Mondal, M.Sc., Entomology

17. MUTATION
&
MEIOTIC RECOMBINATION
RAW MATERIAL
FOR EVOLUTION
©Priyankar Mondal, M.Sc., Entomology

18. ©Priyankar Mondal, M.Sc., Entomology

19. Small scale mutations:
©Priyankar Mondal, M.Sc., Entomology

20. ©Priyankar Mondal, M.Sc., Entomology

21. Point mutation
©Priyankar Mondal, M.Sc., Entomology

22. ©Priyankar Mondal, M.Sc., Entomology

23. Indel
©Priyankar Mondal, M.Sc., Entomology

24. Genes are nothing but stretches of DNA
that code for distinctive type of RNA and
consequently a distinct protein product!!
Alleles are different versions of the same
gene which differ in base sequences!
SO….,
Any type of change in the base sequence
in DNA can be understood as
Mutation
©Priyankar Mondal, M.Sc., Entomology

25. ©Priyankar Mondal, M.Sc., Entomology

26. DNA: C C G C T G C C
T
RNA: G G C G A C G G
A
Replacement or
Nonsynonymus
substitution
Synonymus or silent
substitution
©Priyankar Mondal, M.Sc., Entomology

27. alterations to DNA due to chemical degradation and
replication errors must evade correction to become
persistent mutations.
Tina Albertson and colleagues studied genetically
engineered mice whose DNA polymerases lacked the
ability to proofread and correct newly synthesized
DNA. The mice suffered high rates of cancer and had
dramatically reduced life spans
©Priyankar Mondal, M.Sc., Entomology

28. Fate of point mutation:
Creates new alleles subjected to selection
©Priyankar Mondal, M.Sc., Entomology

29. Gene duplications
Unequal cross-over Retroposition©Priyankar Mondal, M.Sc., Entomology

30. The douc has an unusual diet
for a monkey: It eats leaves.
The leaves are fermented by
bacteria living in the
monkey’s foregut. Further
along the digestive tract, the
monkey digests the bacteria
and absorbs the nutrients
they contain.
©Priyankar Mondal, M.Sc., Entomology

31. Zhang and colleagues (2002) worked on the Douc langur
(Pygathrix nemaeaus) where they found one extra copy of
RNASE1 enzyme having similar introns like RNASE1 of most
related langurs. The simplest explanation is that the RNASE1B
gene in doucs arose as a recent duplication of the monkey’s
RNASE1 gene. ©Priyankar Mondal, M.Sc., Entomology

32. Fate of duplicated genes:
1.Retain their original function and provide
additional copy to the parent gene
2.Gain new function through mutation
3.Become functionless through mutation
(Pseudogenes)
©Priyankar Mondal, M.Sc., Entomology

33. Inversion
Lock the alleles
creating Supergenes!!
©Priyankar Mondal, M.Sc., Entomology

34. Genome duplication and Polyploidy
Polyploidy is common among plants and
has been, in fact, a major source
of speciation in the angiosperms.
At the same time polyploidy causes a
rapid increase in genetic material of a
species which can further be subjected to
modification
©Priyankar Mondal, M.Sc., Entomology

35. Mutation rate
Mutation rates vary among loci in the genome, among individuals, and among kinds
of organisms.
©Priyankar Mondal, M.Sc., Entomology

36. Mutation rates are diverse, spanning several
orders of magnitude.
Different kinds of organisms have different
rates.
Mutation rate clearly evolves.
Are the most mutations beneficial?
©Priyankar Mondal, M.Sc., Entomology

37. 25% LETHAL
40% Neutral
Others are deletorius
Joan Peris and colleagues (2010) induced 100
random point mutations which created the result as
following:
©Priyankar Mondal, M.Sc., Entomology

38. KEY IDEA IS THAT…..
Individuals well adapted to environment
will experience deletorius effects due to
mutation resulting into lower fitness
whereas,
Individuals with high mutation rate
will be favoured in a rapidly changing
environment where there are more
chances for mutations to be beneficial…!!
©Priyankar Mondal, M.Sc., Entomology

39. Thank You©Priyankar Mondal, M.Sc., Entomology