BIOL 1010 Lecture Notes - Lecture 15: Molecular Phylogenetics, Monophyly, Polyphyly
Phylogenetics and Systematics
November 25, 2014
Systematics – study of the diversity of life
TWO CONCEPTS:
1. Taxonomy – naming and identification of taxa (species and groups of species)
2. Phylogenetics – estimation of evolutionary trees (phylogenetic trees/phylogenies)
Taxa and Hierarchical Classification
All of these named groups are taxa.
Leopards are members of every taxa listed.
Binomial Names: Genus species ex. Panthera pardus
*NOTE: know hierarchy Family-Genus-Species
Taxonomy and Phylogeny
• Hierarchical nested taxonomy is consistent with the tree-of-life
• Most biologists today consider that taxonomy should reflect phylogeny
o i.e. Taxa should be monophyletic
Phylogenetic Trees:
• Tips represent examined units (often species)
• Branch points (internal nodes) represent ancestors
• Rotating the nodes or branches of the tree has no impact on the meaning or
significance of the diagram or information given
• Internal nodes do not have to be labeled
• Cladogram – branch lengths have no particular meaning
o Only intention is to show what species are related
• Phylogram – branch lengths represent (inferred) amount of evolutionary change
o Commonly used for molecular phylogenies
o Intention is show what species are related by representing the amount of
evolutionary change
Phyletic Groups on Trees:
Monophyletic Group (Clade) – an ancestor and all of its descendants
Paraphyletic Group – an ancestor and some, but not all, of its descendants
Polyphyletic Group – A group that does not include its most recent common ancestor
find more resources at oneclass.com
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Document Summary
Systematics study of the diversity of life: taxonomy naming and identification of taxa (species and groups of species, phylogenetics estimation of evolutionary trees (phylogenetic trees/phylogenies) Taxonomy and phylogeny: hierarchical nested taxonomy is consistent with the tree-of-life, most biologists today consider that taxonomy should reflect phylogeny i. e. taxa should be monophyletic. Internal nodes do not have to be labeled: cladogram branch lengths have no particular meaning, phylogram branch lengths represent (inferred) amount of evolutionary change. Monophyletic group (clade) an ancestor and all of its descendants. Paraphyletic group an ancestor and some, but not all, of its descendants. Polyphyletic group a group that does not include its most recent common ancestor. Intention is show what species are related by representing the amount of evolutionary change. Phyletic groups on trees: land plants are a monophyletic group (plantae, reptiles are a paraphyletic group, vultures are polyphyletic.
