Frog legs and fish eggs: When scientists compare DNA, there are usually thousands upon thousands—or even millions—of nucleotide bases involved. A computer then scans the sequences and aligns them in a way that provides the best match. In some cases, the computer will add “blank” spaces to improve alignment. Such spaces represent nucleotides that were added or deleted as opposed to changed in one or more lineages. In this level, you’ll get the hang of analyzing DNA by looking at a tiny 4-base snippet. A dash (–) represents either a blank space added to improve alignment or a position that is not important for the analysis you’ve been asked to do. To make things easier, the information from the species compare tab is shown below. However, don’t forget to read the species tabs—they might help you.

Question

Question 3
Position 1 2 3 4
Midas cichlid (outgroup) - C C -
W. Indian Coelacanth - C T -
Western Clawed frog - C T -
On your phylogenetic tree, which two species are grouped together?

 

(1 point)
Responses

Cichlid and coelacanth
Cichlid and coelacanth

Cichlid and frog
Cichlid and frog

Frog and coelacanth

Answer 1

To determine which two species are grouped together based on the provided DNA sequences, we need to analyze the similarities among them.

Here's a breakdown of the sequences:

• Midas cichlid: - C C -
• W. Indian Coelacanth: - C T -
• Western Clawed frog: - C T -

If we consider the base pair positions (ignoring the dashes for alignment):

1. All three species have 'C' at position 2.
2. At position 3, the Midas cichlid has 'C' while both the coelacanth and the frog have 'T'.

From this information, we can see that the coelacanth and the frog share the same nucleotides (C and T) in positions 2 and 3, while the cichlid has a different nucleotide at position 3 (C instead of T).

This suggests that the coelacanth and the frog are more closely related to each other than to the cichlid.

Therefore, the correct response is:

Frog and coelacanth