Phylogenetic Tree

Rooted Tree: All organisms have a common ancestor, known as the out-group.
Un-Rooted Tree: No known common ancestor.; Relative measure of how closely related they are.
Cladograms: Doesn't have a time reference.

Parts of a Tree

Node

Represents averaged ancestral state, not single organisms.

Internal Node: Contains sub-nodes.; Represents a population common to two different branches.

Terminal

Outermost point.

Represents specific organisms.

Branch

Organisms of the same branch share the same feature or trait.

LUCA: Last Universal Common Ancestor
Clade: Ancestral population and all its descendant populations.; Every child node from an internal node (including all terminal species under those nodes).
Sister Clade: Most closely related clades.
Sister Species: Most closely related species.

Apomorphy Derived Trait

A novel character or character state that has evolved from its ancestral form.

Synapomorphy

Trait present in a common ancestor and shared exclusively by its descendants.

Sometimes a synapomorphy is lost during evolution

Snakes lost their 4 legs from ancestors.

Horizontal Gene Transfer

Organisms engulfing others and creating organelles -> genes swap between branches.

Law of Parsimony Law of Simplicity

The one that makes the fewest assumptions and simplest explanation, but not too simple, is the right one.

Data Sources

Morphology: Physical form & structure.
Development: Stages of development.
Fossil Record: Bone dating/traits.
Behavior: Personality
Molecular Data: Genetic Differences; Because of gene transfer, looking at multiple genes/traits is better.
Geography: Where something originated.

Groups

Features