Phylogeny, Trees, & Cladistics Notes

Phylogeny, Trees, & Cladistics

Understanding Trees

• Trees: Represent evolutionary relationships and phylogenetic histories.
    - Root (Basal): The base of the tree, representing the most ancient lineage.
    - Sister Taxa: Groups that share an immediate common ancestor and are more closely related to each other than to any other groups.
    - Node: Points at which branches split, representing common ancestors.
    - Internode: The section of a branch between two nodes.
    - Terminal Branch: The final branch that leads to current species.
    - Nodes can pivot; the same tree can be presented in multiple orientations.

The Olden Days of Evolutionary Thought

• Scala Naturae: An outdated linear model of the complexity of life, viewing organisms as