Reading a Phylogenetic Tree The Meaning of Monophyletic Groups by David Baum Nature Education 2008 www.nature.com/scitable PowerPoint presentation prepared by Larry Flammer ENSI Webmaster

What an Evolutionary Tree Represents

Zoooooming out…

OVERVIEW

Branching pattern of four species

Phylogenetic terminology Terminals / Taxa

A monophyletic group = CLADE

How to Read an Evolutionary 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 of Phylogenetic Trees 1. Increasing use of phylogenetic trees in the biological sciences 2. Need to know what trees diagrams do and do not communicate 3. Provide an efficient structure for organizing biodiversity info 4. Develop accurate conception of totality of evolutionary history 5. Important for aspiring biologists to develop this understanding