Phylogenetic tree in microbial taxonomy 1st sem MSc

1. Phylogenetic tree

2. content
1. Phylogeny
2. Phylogenetic tree : definition.
3. Origin of phylogenetic tree.
4. Types of phylogenetic tree.
5. Construction of phylogenetic tree.
6.significance of phylogenetic tree.
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3. PHYLOGENY
Phylogeny is the study of the
history of the evolution of a
organism species or group.
OR
Study of evolutionary relationships
between species or organism.
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4. PHYLOGENETICTREE
 Diagrammatic representation.
 It shows the evolution of the organisms or species.
 It shows the relationship between the species or the
group of organism. Also called “Tree of life” or
“dendrogram”.
 Referred as two dimensional graph as it represents the
evolutionary relationship between an organism from
various other organism.
 Derived from the ancient Greek word, which refers to
race,origin,or lineage.
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5. origin/ historyof phylogenetictree.
Carl Woese’s Classification
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6. Carl Woese’s Classification is also known as
the Three-domain system.
This classification system divides the life forms
into three domains and six kingdoms, that is why
it also called the Six Kingdoms and Three Domains
Classification.
The three domains are archaea, bacteria,
eukaryote, and six kingdoms are Archaebacteria
(ancient bacteria), Eubacteria (true bacteria),
Protista, Fungi, Plantae, Animalia.
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7. Woese classified them based on
their differences in the 16S
ribosomal RNA (rRNA) structure.
Carl Woese used the rRNA as
an “Evolutionary
Chronometer” – an evolutionary
time clock. KKR1116 7

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9. TYPES OF PHYLOGENETIC TREE
•ROOTED TREE
•UNROOTED TREE
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10. ROOTEDTREE
• A rooted phylogenetic tree is a type of
phylogenetic tree that describes the
ancestry of a group of organisms.
• Importantly, it is a directed tree, starting
from a unique node known as the recent
common ancestor.
• Basically, the roots of the phylogenetic tree
describe this recent common ancestor.
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11. ROOTEDTREE COMPONENTS
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12. EXAMPLE OF ROOTED TREE
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13. UNROOTED TREE
• The unrooted phylogenetic tree is a type of
phylogenetic tree that only describes the
relatedness of a group of organisms.
• Importantly, the leaf nodes of this type of
phylogenetic tree only show relatedness,
not the ancestry.
• Hence, it does not start with the recent
common ancestor and does not contain a
root.
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14. Diagrammaticrepresentationof rootedand
unrootedtree.
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15. EXAMPLE OF UNROOTED TREE
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17. Construction of phylogenetic tree
There are two different methods based on
which phylogenetic tree is constructed.
A. Distance based method
B. Character based method
i. Maximum parsimony .
ii. Maximum likelihood.
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18. Distance Base Method
 This method is based on the amount of the
distance or the dissimilarity between the
two aligned, sequences.
 in this method of constructing the
phylogenetic tree The sequence data is
transformed into pairwise distance and then
the matrix is used for building a tree
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19. Construction of phylogenetic tree by distance
based method
1. ATCGTGGTACTG
2. CCGGAGAACTAG
3. AACGTGCTACTG
4. ATGGTGAAAGTG
5. CCGGAAAACTTG
6. TGGCCCTGTATC
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20. A. ATCGTGGTACTG
B. CCGGAGAACTAG
C. AACGTGCTACTG
D. ATGGTGAAAGTG
E. CCGGAAAACTTG
F. TGGCCCTGTATC
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21. A B C D E F
A 9 2 4 9 10
B 9 6 2 10
C 5 9 10
D 6 10
E 10
F
A
B
C
E
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22. A/C B D E F
A/C 9 4.5 9 10
B 6 2 10
D 6 10
E 10
F
A/C B/E D F
A/C 9 4.5 10
B/E 6 10
D 10
F
A
C
D
E
B
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23. FINAL STEP
A/C/D B/E F
A/C/D 7.5 10
B/E 10
F
F
E
B
D
C
A
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25. MAXIMUM PARSIMONY
• It is a method to find out the
tree which has small possible
number of mutations.
• It is a method which uses only
few characters.
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26. Maximum parsimony
taxon 1 2 3
A G G G
B G T G
C T G T
D T T T
G G T T
A B C D
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27. Maximum likelihood
• It is a method of construction of
phylogenetic tree by the probability
method.
• By finding the probability between
two characters or sequences the
tree is constructed.
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29. Significanceof phylogenetictree
 It is the fundamental tool to derive
their most useful evidence from the
fields of anatomy, embryology,
paleontology and molecular
genetics.
 Used in search of new species.
 Used to study evolutionary histories.
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30.  To study how species were spread
geographically. To study common
ancestors of extant and extinct species.
 To represent evolutionary relationships
between organisms that are believed to
have some common ancestry.
 With the help of phylogenetic tree, the
infectious microbes can be traced along
with their evolutionary histories.
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31. references
• NCBI
• Cold spring harbor protocol.
• Phylogenetic tree -Full theory
explanation CSIR – NET
(YouTube)
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32. Thank you .
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