Part G-Making a phylogenetic tree from a distance matrix Now that you have a dis

Question

Part G-Making a phylogenetic tree from a distance matrix Now that you have a distance matrix, the next step is to show these relationships graphically with a phylogenetic tree. There are a number of ways to make a phylogenetic tree, but the simplest method uses the information from a distance matrix to cluster more similar samples together into a related group, also known as a clade.In the trees below, the horizontal distance along each line reflects the percent difference between each of the samples. The scale beneath each tree tells you how far along a branch you have to go to have a 0.01 (1%) difference in sequence Which of the following trees is the best match for the relationships shown in the distance matrix? (See Hints 1 and 2 for help.) O. keta O. nerka O. kisutch O. tshawytscha S. salar Test sample 0.01 O. nerka O. kisutch O. keta O. tshawytscha S. salar Test sample 0.01 O. nerka O. keta O. kisutch O. tshawytscha S. salar Test sample 0.01 O. nerka O. keta O. gorbuscha Test sample O. tshawytscha O. kisutch S. salar 0.01

Explanation / Answer

A cladogram is a bit more difficult to interpret, but if you see the table that gives you the percentage of how related is a kind of the other you can help a lot.

Now, S. salar has a 1% difference with respect to the "Test sample", so having so little difference must be in the same branch, so the last phylogenetic tree is wrong because "Test samnle and S. salar are in different branches.

Now to discard more options, look for another couple that is very close so you can see what options match the data, the next couple more related is O. kisutuch and O. tshawytcha which only have a 4% difference and it is valid to assume that they must be in the same branch. Now with this you can say that the second tree is wrong because it puts these two species in different branches.

Now that you have two discarded options look for another group that is related, O. keta and O. gorbuscha would be the next members that are more related having a 5% difference so we can assume that they must also be in the same branch, although in the fourth tree appear in the same group this was already discarded, the first tree puts these two members in separate groups, so it is valid to say that it is wrong.

We can conclude that the third tree is the correct one

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