Molecular Phylogeny
course: Sequence Information
Students:
Razick Ahmed Sabry
Mehio Wissam
Lydakis Apostolos
Sathyanara Tejashwari
Introduction – Growth hormone
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Growth hormone (or somatotropin) is a protein hormone of
about 190 amino acids
Synthesized and secreted by cells called somatotrophs.
A major participant in control of several complex physiologic
processes, including growth and metabolism.
Also of considerable interest as a drug used in both humans and
animals.
Methods of Phylogeny
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Maximum Parsimony: Optimal tree is the one with the fewest
mutations.
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Maximum Likelihood: Assigns probabilities to mutations. The
optimal tree is the one with highest probability.
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Distance Matrix: The optimal tree is the one resulting from the
least number of inter-species distance and evolution.
Approach 1
Trying to prove (Approach 1)
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Evolution of pituitary growth hormone (GH) in mammals has
generally been very slow but with short bursts of rapid change in
the evolution of some groups. Such a period of rapid change
occurred in the evolution of GH in primates or a primate
ancestor and gave rise to the marked species specificity of
human GH. By cloning and sequencing of GH genes from a
prosimian, the slow loris (Nycticebus pygmaeus), and a New World
monkey, the marmoset, (Callithrix jacchus)it has been shown that
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prosimian GH is similar in sequence to pig GH
while marmoset GH resembles human GH
Approach 1 , Strategy
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Research already done suggests the following
facts,
“The period of rapid change in sequence
for GH during primate evolution
occurred after the separation of lines
leading to prosimians and higher
primates and before divergence of
lineages for New World monkeys and
Old World monkeys/apes.”
Our results of Approach 1
Approach 1 , results suggests
New world monkey
Prosimians and higher
primates
Human
Old world monkey
Mammals
Other mammals
Conclusion from Approach 1
New world monkey
Prosimians and higher
primates
Human
Old world monkey
Mammals
Other mammals
Approach 2
Distance Matrix
Maximum Parsimony
Maximum Likelihood
Biological Interpretation
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It is obvious from the previous results that the human GH is
different from that of the rabbit, pig, elephant, dog, cat, and
alpaca. The trees suggest that the primates have a different GH
than that of the other mammals. This hypothesis was proved by
when lab experiments showed that only human and primate
growth hormone have significant effects in humans, which
suggests that the receptor for GH has also mutated in primates.
It is noteworthy that GH tends to be similar among species that
have similar looks, sizes, and body functions.
Some studies showed that the “Slow Loris” constitutes the
turning point of the evolution of GH among mammals, but the
sequencing we conducted showed nothing of that, in fact the
Slow Loris tended to show similarity with
Conclusion
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Somewhere along the line of evolution of mammals there is a
sharp mutation in GH, which led to the formation of primates.
The latter evolved more and more to yield up species like
chimpanzee and homo sapiens.
Macaca
Back to Tree
Callithrix
Back to Tree
Slow Loris
Back to Tree