Question

which is the best description of the two organisms highlighted in orange?
○ they are separated by two nodes.
○ they share a recent common ancestor.
○ they belong to the same species.
○ they are ancestors of each other.

Explanation:

To determine the best description, we analyze each option:

• "They are separated by two nodes": Looking at the phylogenetic tree, the two organisms (crocodile and bird) share a common ancestor at a single node before their divergence, so they are not separated by two nodes.
• "They share a recent common ancestor": In a phylogenetic tree, organisms that diverge from a relatively close (recent) node in the tree share a recent common ancestor. The crocodile and bird in the orange box diverge from a single common ancestor node, indicating a recent common ancestor.
• "They belong to the same species": A crocodile and a bird are clearly different species.
• "They are ancestors of each other": A crocodile is not an ancestor of a bird, nor vice versa; they diverged from a common ancestor.

Answer:

B. They share a recent common ancestor.