The Tree of Life

 A phylogenetic tree is a diagram that represents how life on Earth is all connected to one another. It is called a tree because the diagram looks like a tree. It looks as if it has a trunk and branches. The trunk of the diagram represents the first common ancestor from the group of organisms that are being looked at.  

There are a few different types of phylogenetic trees and today we are going to look at 2 different types, monophyletic and paraphyletic. 

There is an example of a phylogenetic tree below. You can see at the left side of the picture that there is a trunk and the diagram extends into branches. This diagram is showing how water living creatures are related to one another. 

This tree is a monophyletic tree. All of the groups connect at a point somewhere on the diagram. This shows that they all have a single common ancestor.  

This phylogenic tree is a paraphyletic tree. A paraphyletic tree shows how a group of organisms are related but it leaves out a group that is connected to the same common ancestor as the group you are focused on. The group we are looking at above is circled in green. You can see that the rainbow opossum is not included in the circled group even though it is connected at the same common point as the green circled group of animals.