BIO153H5 Lecture Notes - Lecture 4: Linnaean Taxonomy, Willi Hennig, Paraphyly
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Bioology Lecture 4
Cladistics: phylogenetic systematics
• Synapomorphies provide the only evidence for identifying recent common ancestry
• only monophyletic groups are permissible in a cladistic taxonomy
• Willi Hennig 1913 – 19
• Didn’t face much antagonism
reconciling cladistics and Linnaean taxonomy
• Linnaean taxonomy is rigid – 7 hierarchical levels (defined subjectively); number of
levels in a cladistic analysis varies
• Linnaean taxonomy permits paraphyletic groups: “fish”; “reptiles”; cladistics does not
Outgroup
• Roots the tree, how you construct the tree
• Cladogram or tree
• QUESTION : neither is, appreciate where do the nodes join
• Branches join at node D
Most parsimonious tree: evolution of bipedalism less complex than evolution of placental
development.
Identified as one chsrecter, but there is a lot more to just this.
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