One fish, two fish, red fish, lungfish: For a long time, scientists thought that coelacanths were the closest living relatives to amphibians. Coelacanths have big fleshy fins and hinged jaws, two traits they share with fossils of ancestral amphibians. When they went to analyze the DNA, however, they got a surprise. Take a look at the data yourself and see what you come up with.

Question

Position 1 2 3 4 5 6 7 8 9 10
Great white shark (outgroup) C - C T - - - - - T
Midas cichlid C -
C

C - - - - - T
S. American lungfish T - C C - - - - - A
W. Indian coelacanth T - C C - - - - - T
Western clawed frog T - C C - - - - - A
Scientists previously thought that frogs and coelacanth are most closely related due to physical characteristics. With DNA evidence, we now know that frogs are more closely related to which of the following?

(1 point)
Responses

Cichlid
Cichlid

Lungfish
Lungfish

Great white shark

Answer 1

Based on the DNA data provided, the results show that the Western clawed frog and the S. American lungfish share more similarities in their genetic sequences compared to the Western clawed frog and the coelacanth or the cichlid. The coelacanth has multiple differences in its DNA compared to the frog.

Thus, scientists now understand that frogs are more closely related to the lungfish than to the coelacanth or cichlid.

So, the correct response is Lungfish.