Cladograms and Common Ancestors

Cladogram Vertebrata by Biology Dictionary Editors

One of the most common things known amongst people who have studied evolution is that we all share a common ancestor. But how do we figure out which one we are the closest related to? The simplest thing to use is a cladogram. A cladogram shows us traits that certain organisms share, who their closest relative is and what common ancestor is shared most recently between organisms. A cladogram consists of a line climbing diagonally upwards, diagonal lines branching off of the baseline, the name or a picture on the top of one of the branches and a list of traits shared by the organisms as we go further up the diagram, below the baseline at certain points. To make a cladogram you first identify all of your organisms. Then you make a table of the organisms and their traits. Go through the table, it the organism has the trait, put a plus sign, if it doesn't, put a minus and if you don't know, put a question mark. Then make a Venn diagram, but not your usual two circles Venn Diagram. Start by drawing one big circle. At the bottom, put the most common trait and the organisms that share it. Then draw another circle inside that first circle. In this one write the next most common trait and the organisms that share it. Continue to do this until you have listed all of the traits. You are now ready to build your cladogram. Draw a line at the bottom of your diagram, this line represents time. Then draw a line branching off of the one you just drew, for every organism you have. Leave space at the top. You will then look at the center of your Venn diagram, you will most likely have one organism and the trait that only it has. Take that one organism and put it on the line at the front of the baseline. This would be the most recent. Then put the trait that it shares, beneath it where the organisms line meets the timeline. Then move o to the second smallest circle in your diagram. You then choose the organism that is not yet on your cladogram. Place it and the trait on the cladogram. Repeat these steps until all of the organisms and traits are on your cladogram. You can now figure somethings out. At the spot where the organisms line meets the line of time, you will have a common ancestor of that organism and the ones above it. The closer the organism is to this spot, the more recent the common ancestor, the closer they are related. You can also use this to figure out what two animals are more closely related. If they share a more recent common ancestor, they are more closely related. You can use cladograms to sort and classify organisms, as well as figure out things like common ancestors, close relatives and who the organism evolved from. Cladograms tell us a lot of things, no wonder they are so common.

S&EP
SP2: Using Models

A cladogram is a big model that helps scientists all over the world to understand organisms. Cladograms help people to figure out many things. But to make a cladogram you need other models. These include Venn diagrams and tables. These are two very useful, visual, diagrams that can help you no matter what you are looking for. Cladograms and the process to get them includes many models that make life easier for people.

XCC
XCC: Structure and Function

Cladograms are a type of structure that has many functions. A cladogram is a simple structure of lines and words. It has many different functions. These include showing us traits that are shared, like spikes, claws and hair. It also shows us who certain organisms are more closely related to. Like Bears and Birds or Bears and Monkeys. They also show us common ancestors, like bacterias and other more recent and complex organisms. Cladograms are simple to construct, and tell you a lot about certain organisms, this is why they are used so often.