SAT Subject Biology Practice Question 165: Answer and Explanation

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Question: 165

15. Scientists constructed a phylogenetic tree of modern lizard genera based on DNA sequences, shown below.

Which genus can be identified as the closest relative of the genus Pletholax?

A. Delma
B. Aprasia
C. Paradelma
D. Lialis
E. Pygopus

Correct Answer: B

Explanation:

In the diagram, it is implied that time moves from left to right. The most closely related groups will be on branches that diverge from a common point farthest to the right on the diagram, or most recently in time. The genera Pletholax branched from a common point shared by Aprasia (and Ophidiocephalus) more recently than any other genus.

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