PP Notes Chapter 26 Cladistics - part 1 Winter 2012

5 phylogenetic trees branch point where lineages

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Unformatted text preview: gure 26.5 Phylogenetic Trees Branch point: where lineages diverge Taxon A Taxon B Taxon C Sister taxa Taxon D ANCESTRAL LINEAGE Taxon E Taxon F Taxon G This branch point represents the common ancestor of taxa A–G. Basal taxon This branch point forms a polytomy: an unresolved pattern of divergence. 1 1/16/2012 Limits of phylogenetic trees Phylogenies have other applications besides classification No No indication of when an event happened (time is relative not absolute) No No indication of amount of change that occurred cannot cannot infer that one sister taxa evolved from another (only that they share common ancestor) Searching for Homology Morphological Morphological and molecular similarities among living organisms Organisms Organisms similar in appearance also are often similar in molecular make-up (DNA and makethus protein sequences) WHEN WHEN IS THIS NOT TRUE? Homo...
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