Cladograms 11/2

Cladograms are the charts scientists use to show how closely related organisms are and what traits they share. Cladograms are helpful because they can show you where the common ancestor of two or more organisms is and what organisms share traits.

Venn diagrams are helpful when building a cladogram. The organisms, traits and names can get mixed up, and venn diagrams help organize the information.

To see how cladograms work, let’s build one. Here are five organisms:

There are a lot of similarities between these five organisms. Let’s organize them in a venn diagram before building the cladogram to make it a little bit simpler.

Images

Notice how we eliminate one organism as we move towards the center of the venn diagram. All five of the organisms have a backbone, but snakes don’t have four limbs, so they were eliminated from the next box. Humans don’t have tails, so they were removed from the next box on. Tigers eat meat, but cows and giraffes are herbivores. And giraffes have those horns on their heads. (You might argue that cows have horns, but this specific breed does not.)

We can now move on to building the cladogram. We start at the middle of the venn diagram and move outwards.

We need to fill in the names of the organisms and the pictures at the top in the empty box and the traits where the red lines are. We’re going to go right to left, starting with the giraffe.

Images

We can look at the first red line underneath the snake and know that every organism to the right of it has a backbone. That is true for every red line. When we look at the line that says tail, we know that the organisms to the right (tiger, cow and giraffe) have a tail and that the organisms to the left (human and snake) don’t have a tail.

Cladograms help us see which organisms are closely related and which share traits with each other.

S&EP: SP2 Using Models

A cladogram is a model that scientists use to show which organisms are closely related and which share traits with each other. Cladograms are helpful because they help organize the information and make it clearer to see. I used cladograms to determine the closest relative of the T-rex and estimate what it most likely tasted like. Using information found at T-rex closest relative, we compared information and found that the T-rex’s closest relative is the parrot, meaning that the dinosaur probably tastes most like chicken. Using the cladogram was helpful for me because there were multiple organisms that were closely related to the T-rex, and using the cladogram helped me figure out which one was the most closely related.

XCC: Structure and Function
While I was studying the T-rex’s closest relative, there were several interesting things I noticed about its structure that I didn’t notice before. Both the T-rex and the parrot have fingers, even though the parrot’s look like they are hidden in its wings, which they are. I noticed that both organisms were missing their four and fifth fingers, unlike the caiman, another close relative. The T-rex and parrot also are bipedal, meaning they walk on two legs. Using the cladogram helped me discover this new information and compare it to new information.

Image links:

Cow: https://upload.wikimedia.org/wikipedia/commons/6/65/201409_cow.png by Wikimedia Commons

Snake: snake-3254415_960_720.png by Pixabay

Giraffe: giraffe-1151683_960_720.png by Pixabay

Tiger: animal-2057646_960_720.png by Pixabay

Human: woman-2859008_960_720.png by Pixabay