The most closely related groups in the phylogenetic tree are Felidae (cats) and Canidae (dogs). We can determine this by examining the branching pattern on the tree.
1. Felidae and Canidae share a more recent common ancestor compared to the other groups on the tree. This is indicated by a point on the tree where the branches leading to cats and dogs come together before branching out to separate groups.
2. The point at which branches split represents a divergence in the evolutionary history of these groups. The closer the split is to the root of the tree, the more closely related the groups are considered to be.
3. In this case, since Felidae and Canidae branch off from a common point closer to the root of the tree than Phocidae (seals) or Ursidae (bears), it indicates a closer evolutionary relationship between cats and dogs.
Therefore, based on the phylogenetic tree and the branching patterns, Felidae (cats) and Canidae (dogs) are the most closely related groups among the four shown.
