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Can somebody help me understand this phylogeny question?


EvoBioChemo

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I was looking at some of the Chapter questions in my Evolution textbook (Evolution: Making Sense of Life by Zimmer and Elmen), and I came across this question that is just stumping me in Chapter 4. The question states:

5) In the past, morphological evidence alone was used to examine the relationships of the cetaceans to other groups. According to this phylogency (which I had attached):

a) The extinct genus Ambulocetus is more distantantly related to the genus Balaenoptera than to the extinct genus Protocetus.

b) The genus Equus (horses) is more closely related to the genus Hippopotamus (hippos) than to the extinct genus Pakicetus.
c) More changes have occured in the whale lineage than in the horse lineage.

d) Horses (genus Equus) were the ancestor of whales and hippos.
e) None of the above are correct statements
f) All of the above are correct statements.

The back of the book says that the correct answer is "e) None of the above are correct statements", but I was having some trouble seeing why for a while. Here is my reasoning behind why I chose e, and if you guys could help to critique my understanding if it is incorrect, that would be awesome.

a) This cannot be because Ambulocetus is equally related to both of those two genera. This is because they all share a recent common ancestor before the lineage of Ambulocetus diverges from the lineage of the rest of the phylogeny.
b) This cannot be because, again, they are equally related.
c) I honestly do not know the answer for this one, but my guess comes from the fact that it is not mentioned how many changes occur in the phylogeny.
d) Horses split from the common ancestor of this clade before it seperated off into the brown and blue clade

Again, I'm not looking for an answer since I already know it, I just want to know if my reasoning is solid, and if not, maybe a suggestion as to why it isn't. Thank you!


Bear with me guys, it won't let me upload the picture. Sorry about that.

Edited by EvoBioChemo
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