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Published byLaurel Small Modified over 9 years ago
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Phylogenetic Trees Importance of phylogenetic trees What is the phylogenetic analysis Example of cladistics Assumptions in cladistics Frequently used terms Fundamentals of Phylogenetc models Phylogenetic software
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Importance of Phylogenetic Tree Classification is important to understand Evolutionary history of an Organism Study of Biological Diversity Organization Progressive Multiple Sequence Alignment
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What is Phylogenetic Analysis Study of evolutionary relationship Inferring or estimating relationship Usually presented as branching, tree Gene Tree: Inherited relatioships It is also called cladistics clade means branch in Greek Member of group/clade share a common rel.
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Example of Cladistics
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Assumptions in Cladistics Any group of oragnisms is related by descent from a common ancestor Members of a group or clade share common evolutionary history A group sharing a unique feature, different from other groups There is bifurrcating pattern of cladogenesis Change in charterstics occurs in lineages over time
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Frequently Used Terms Clade: A monophyletic taxon. Clades are group of organisms Taxon: Named group or organisms but not necessarily a clade Branch Length: In some case it repersent divergence Node: A bifurcating branch point
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Fundamentals of Phylogenetic Models Sequence alignment (AMPS,Clustal-W) Substitution model (weight model) –Rates between Bases –Site Substitution(overall compositional change) Tree building Tree Evaluation
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Tree Building Distance Based Methods –UPGMA: Unweighted Pair Group Method It is a Clustring algorithm, it cluster tree branches based on greatest similarity among pairs and averages of joined pairs –NJ: Neighbor Joining First, it join nearest pair in start and then continue till one remain Character-Based –Maximum Parismony (MP) –Maximum Likelihood (ML)
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Tree Evaluation Randomize Tree Randomize Character Data Bootstrap Likelihood Test
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PHYLIP PAUP PUZZLE TreeDraw MACCLAD Web Based –webphylip, PhyloBlast
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