Phylogenetics+and+speciation+Lab+03 - Phylogenetic inference Cladistics is a method of hypothesizing relationships among organisms Read 26.1-26.3

Phylogenetics+and+speciation+Lab+03 - Phylogenetic...

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Phylogenetic inference Read 26.1-26.3 Cladistics is a method of hypothesizing relationships among organisms
Phylogenetic inference Definitions: Apomorphy: Derived character Synapomorphy: Shared derived character Plesiomorphy: ancestral character A B C D apomorphy synapomorphy plesiomorphy
CLADOGRAM: is comprised of branches and nodes E B C D E A B C D
CLADOGRAM: is comprised of branches and nodes E A C D B C
Phylogenetic inference Read 26.1-26.3 Phylogenetic trees are built from “characters” • characters can be morphological, behavioral, physiological, or molecular. • there are two important assumptions about characters used to build trees: 1. they are independent 2. they are homologous
2. Any group of organisms is related by descent from a common ancestor. Homology vs. Convergent Evolution (homoplasy)
Homoplasy
3. There is a dichotomous branching pattern of lineage-splitting.
Choose the taxa whose evolutionary relationships interest you Choose an outgroup- a taxon outside the clade Determine the characters and character states Determine the polarity of characters Figure out the order of evolution for each character. Group taxa by synapomorphies Work out conflicts Reconstructing trees: A step by step method
Reconstructing trees: A step by step method

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