Which of the following statement is correct, given this phylogeny of four
species?
A has gone extinct
A is more closely related to C than D
D evolved from C
B, C and D shared a common ancestor
✅ Correct Answer: D) B, C and D shared a common ancestor
Explanation Based on the Phylogeny
A phylogenetic tree shows how species are evolutionarily related based on shared ancestry. In the given diagram:
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B, C, and D form a single clade, meaning they originate from a common branching point.
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A branches out earlier, meaning it is more distantly related to B, C, and D.
Let’s analyze each option:
Option A: A has gone extinct — ❌ Incorrect
Nothing in the phylogenetic tree indicates extinction.
Extinction is usually shown with:
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A branch ending before the present
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A cross mark (X)
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Absence of continuation
Since none of these signs are present, A is not extinct.
Option B: A is more closely related to C than D — ❌ Incorrect
To determine closeness, we compare the most recent common ancestor (MRCA):
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A and C share an ancestor that is older (deeper in the tree).
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C and D share a much more recent ancestor, making them closely related.
Therefore, A is not more closely related to C than to D.
In fact, A is equally distant from both C and D.
Option C: D evolved from C — ❌ Incorrect
This is a common misconception.
In phylogeny:
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Species do not evolve from each other.
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They evolve from a shared ancestor.
C and D are sister species, not ancestors of each other.
So D did not evolve from C.
Option D: B, C and D shared a common ancestor — ✔️ Correct
The phylogeny clearly shows:
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B, C, and D are part of the same clade
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They diverged from a single common ancestor
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This ancestor is not shared with A
Thus, this statement perfectly matches the tree.
🔍 Summary
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The phylogeny shows A diverged first, and B, C, D form their own cluster.
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Only option D correctly describes the evolutionary relationship.
