All life on Earth is united by evolutionary history; we are all evolutionary cousins — twigs on the tree of life. Phylogenetic systematics is the formal name for the field within biology that reconstructs evolutionary history and studies the patterns of relationships among organisms. Unfortunately, history is not something we can see. It has only happened once and only leaves behind clues as to what happened. Systematists use these clues to try to reconstruct evolutionary history.

In this tutorial, we’ll cover:

• How to read an evolutionary tree
• How to classify organisms based on evolutionary trees
• How to reconstruct an evolutionary tree
• How evolutionary trees are used