Evolutionary Trees

Interpreting Evolutionary Trees

1) Species with closer connections on the tree are more closely related. The connection represents a common ancestor. EXAMPLE: Species B is more closely related to species C than to species A. B and C have a closer connection on the tree (a more recent common ancestor).

2) When branches continue, a species evolves. When branches split, a common ancestor is evolving into 2 different species. EXAMPLE: Species H evolved into species F and species A. Species H is the common ancestor of species F and species A.

3) To find a common ancestor between species, trace both of their lines back until the point that they meet. This is the most recent common ancestor. EXAMPLE: The most recent common ancestor of species B and D is species K.

4) Species are at the top of the tree are in the present-day environment. These species are suited for today’s environmental conditions. These species have the traits to survive and compete in the modern environment. EXAMPLE: Species D is alive today and is suited for the modern environment.

5) Species who’s branches end in the past (and did not evolve into anything else), went extinct. These species did not have the traits for survival in a changing environment. These species did not have the adaptations necessary to survive environmental change. EXAMPLE: Species J went extinct- it did not have the adaptations necessary to survive environmental change.