Understanding Evolution: your one-stop source for information on evolution
Resource library Teaching materials Evolution 101
 
EVOLUTION 101

Introduction

Patterns

Mechanisms

Microevolution

Speciation

Macroevolution

The big issues

en Espanol en Español     print print

Understanding phylogenies

Understanding a phylogeny is a lot like reading a family tree. The root of the tree represents the ancestral lineage, and the tips of the branches represent the descendants of that ancestor. As you move from the root to the tips, you are moving forward in time.

Tree showing ancestor and descendants

When a lineage splits (speciation), it is represented as branching on a phylogeny. When a speciation event occurs, a single ancestral lineage gives rise to two or more daughter lineages.

Where a tree branches, there is a speciation event

Phylogenies trace patterns of shared ancestry between lineages. Each lineage has a part of its history that is unique to it alone and parts that are shared with other lineages.

Tree showing unique and shared lineages

Similarly, each lineage has ancestors that are unique to that lineage and ancestors that are shared with other lineages — common ancestors.

Tree showing location of unique and common ancestors

Download this series of graphics from the Image library.



previous
The family tree

  next
Understanding phylogenies (2 of 2)


Patterns
page 3 of 11
previous | next  >


More details
In some phylogenies, more than two daughter lineages arise from a single ancestral lineage. Find out how to interpret these trees.


Teach this
Teach your students about evolutionary relationships and phylogenetics:

Find additional lessons, activities, videos, and articles that focus on phylogenetics.