Interpreting a cladogram Animation

Using a cladogram to determine relative relatedness and whether the lungfish is more closely related to a human or to a trout. To determine the relative relatedness, we begin by tracing the branches from the human and the lungfish to the point where they meet. We'll call this node 1. Now, we'll trace back the lungfish and trout branches to their intersection and call this node 2. As you can see, the trout-lungfish intersection at node 2 is nearer to the base of the tree than the human-lungfish intersection at node 1. This means that the lungfish shares more derived characteristics with the human than it does with the trout. Another way to think about this is to regard the vertical axis of the cladogram as a time bar, but without absolute dates. The lower the position of the branch point between two groups, the more distant is their most recent common ancestor.

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