Figure 27.24 - Rooting a tree with an outgroup. (A) Unrooted tree.

Figure 27.24. Rooting a tree with an outgroup. (A) Unrooted tree. (B) Suppose species 3 is determined to be the outgroup. Then the tree can be rooted between 3+ other taxa (root shown as red dot). Branches are labeled with letters for easier comparison of B and C. (C) Rooted tree.

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