Elements of Phylogeny

The evolutionary divergences are strictly bifurcating, so that the observed data can be represented by a treelike phylogeny. 

The sequence is correct and originates from a specific source. 

If the sequences analyzed are homologous, they are descended from a shared ancestral sequence. 

Each multiple sequences included in a common analysis has a common phylogenetic history with the others. 

The sampling of taxa is adequate to resolve the problem of interest. 

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