Reading a Phylogenetic Tree

The Meaning of Monophyletic Groups

by David Baum

Nature Education 2008

www.nature.com/scitablePowerPoint presentation prepared by Larry Flammer

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What an Evolutionary Tree Represents

Zoooooming out…

OVERVIEW

Branching pattern of four species

Phylogenetic terminology

Terminals / Taxa

A monophyletic group = CLADE

How to Read anEvolutionary Tree

Information on patterns of evolutionary decent is the same regardless of the lengths of branches

These trees depict equivalent relationships despite different styles

Equivalent relationships, even though internal branches rotated

Tree shows relative timing of nodes only when nodes are on

same path from root

The Importance ofPhylogenetic Trees

1. Increasing use of phylogenetic trees in the biological sciences2. Need to know what trees diagrams do and do not communicate3. Provide an efficient structure for organizing biodiversity info4. Develop accurate conception of totality of evolutionary history5. Important for aspiring biologists to develop this understanding