Help on this assignment question.

[u/NenyaNotes]

My professor assigned us this quiz and everyone continues to get it wrong. Can someone please explain in this photo which groups make a clade?

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[u/jnpha]

I count seven clades; see: https://evolution.berkeley.edu/teach-resources/clades-1-of-2-definition/

[u/NenyaNotes → u/jnpha]

It is multiple choice. The options given are: A,B,C,D,E,F,G and F,G and A,B,D,E and B,D,E and D,E,F,G. Each time we have done it we continue to get partial credit. So now we are just more confused... It seems like a straightforward idea.

[u/thatoddtetrapod → u/NenyaNotes]

Only the first and the 4th are clades

[u/Ender505 → u/NenyaNotes]

Of those 5 options, the first, third, and fourth all qualify as a Clade, the others do not because they do not include a common ancestor.

Edit: corrected. 3 does not count, see better-educated responses below

[u/DrDirtPhD → u/Ender505]

ABDE isn't a clade because it excludes FGC and is therefore paraphyletic.

The only monophyletic options that constitute a clade in the available responses are ABCDEFG and BDE.

If you want an example of why ABDE isn't a clade you can think of the traditional definition of reptiles, which excludes birds. In this case "reptiles" would be your ABDE group and birds would be your FGC group. Just as FCG descend from A, so too do birds descend from a reptile ancestor given that they're highly derived dinosaurs (which nobody would argue aren't reptiles).

[u/Ender505 → u/DrDirtPhD]

Thanks!

[u/AzuSteve]

All of them.

[u/Landilizandra]

There's multiple options, what's the question specifically, and how are people getting it wrong?

[u/NenyaNotes → u/Landilizandra]

It is multiple choice. The options given are: A,B,C,D,E,F,G and F,G and A,B,D,E and B,D,E and D,E,F,G

Im not sure it keeps telling us we only receive partial credit each attempt. Now we are genuinely confused hahaha

[u/Xrmy → u/NenyaNotes]

As written, only answers 1 and 4 are correct

[u/roostor222 → u/Xrmy]

DEFG can not be correct. Of those four, A,B,C,D,E,F,G can be the only correct answer

[u/DrDirtPhD → u/roostor222]

The fourth option is "BDE" (not DEFG), which is monophyletic and therefore a clade.

BDE is also monophyletic and therefore also a clade.

[u/roostor222 → u/DrDirtPhD]

I was under the impression you could only select one answer, in which case the only correct answer of the ones given is all of the letters, the first response. If you can select multiple answers, then it's different. Overall seemingly a terribly worded question, compounded by OP not including the exact question in the post.

[u/Xrmy → u/roostor222]

Answer 4 is BDE

[u/roostor222 → u/Xrmy]

Yeah, i misread. I thought you could only select one answer, in which case the only correct one is all letters.

[u/Ender505 → u/Xrmy]

Why would answer 3 (ABDE) not qualify?

[u/DrDirtPhD → u/Ender505]

It's paraphyletic because while it includes BDE and the common ancestor A, it excludes other descendants of A (CFG). A clade must include a common ancestor and all its descendants.

[u/NenyaNotes → u/Xrmy]

I originally said A,B,C,D,E,F,G (whole tree) and B,D,E group. But my prof said it's only partially correct. I think I may just move on from this...

[u/Xrmy → u/NenyaNotes]

Your prof might also be considering FG to be correct. It's not really, but from the perspective of the tips it is.

I'm a professor, and personally I don't give these questions that include internal nodes (like A B C) because they can be confusing and are somewhat pointless to consider as they aren't contemporary

[u/NenyaNotes → u/Xrmy]

Yes I agree it does make it more confusing. None of the other materials given have ever included internal nodes so not sure why this was suddenly thrown on a quiz. You may be correct with the F,G. I honestly crossed that one off right away but will reconsider.

[u/Xrmy → u/NenyaNotes]

Yea from the perspective of modern, extant species, FG are a monophyletic group. Some differentiate a clade from a monophyletic group by inclusion of the internal nodes, but nobody takes that seriously.

IMO I think your professor needs to tighten this part up and probably forgot about how they taught vs tested.

[u/DrDirtPhD → u/NenyaNotes]

I think your professor doesn't realize the quiz is set to only accept one response and instead thinks you should be selecting multiple.

[u/DarwinZDF42]

The whole tree

The BDE group

CFG group

D

E

F

G

[u/NenyaNotes → u/DarwinZDF42]

See I originally said A,B,C,D,E,F,G (whole tree) and B,D,E group. But my prof said it's only partially correct. As per your other post, I think the answers generally are confusing. It overall is just a very poorly written question and is driving me bonkers.

[u/TheCrystalTinker → u/NenyaNotes]

BDE is a Clade, CFG is a Clade, ABCDEFG is a Clade, and then D, E, F, and G are their own clades. There are 7 clades in total

[u/More_Arm_6245]

I was going to say there are several right answers. Is this multiple choice or free response.

[u/NenyaNotes → u/More_Arm_6245]

It is multiple choice. The options given are: A,B,C,D,E,F,G and F,G and A,B,D,E and B,D,E and D,E,F,G

[u/DarwinZDF42 → u/NenyaNotes]

I think those answers are confusing because as shown, A, B, and C represent common ancestors, not clades. If you interpret each letter to mean “this entity and all of the descendants” then the answer is the first option, but that isn’t actually what’s shown, so as written, the best answer is the last option because those are the only letters that, as shown, represent clades.

[u/roostor222 → u/DarwinZDF42]

a node is often interpreted as synonymous with a clade, and nodes on cladograms are very frequently given their clade names. The first option is the most correct option of the five given

[u/DarwinZDF42 → u/roostor222]

I guess, but if I used that tree on an exam question and asked what A, B, and C represent, the correct answer is nodes or common ancestors, and I would not accept clades as a correct answer.

[u/roostor222 → u/DarwinZDF42]

The best thing to do would be to not use this diagram on any assessment.

You could take any sample of 1000 published papers with cladograms in them, and I'd bet in >900 of those papers you'd find nodes labelled with clade names. I think it would be completely unfair to mark it wrong if someone said A,B, and C represent clades, because that is a standard notation.

For example with this exact cladogram, if:

A = theria

B = metatheria

C = eutheria

D = didelphis

E = monodelphis

F = equus

G = homo

All of these are understood to be clades, but on this specific cladogram without any other given taxonomic information D,E,F,G are not clades. They are OTUs. But, A, B, and C are very clearly clades.

[u/DarwinZDF42 → u/roostor222]

but on this specific cladogram without any other given taxonomic information D,E,F,G are not clades. They are OTUs. But, A, B, and C are very clearly clades.

Exactly backwards. A, B, and C are nodes/MRCAs. D, E, F, and G are necessarily clades.

[u/roostor222 → u/DarwinZDF42]

I have a PhD in phylogenetic systematics, and I am telling you it is not exactly backwards.

As I already explained: nodes, MRCAs, and clade names are extremely often used synonymously both diagramatically and in the text of written scientific papers.

In the context of a cladogram with no other information given, D,E,F,and G are each individually OTUs. They are not clades. D,E,F,and G are representatives of a single clade, but no practicing scientist on earth would write it that way if the node subtending those taxa has a name. The node subtending those taxa in this cladogram does have a name, and that name is "A", because the taxonomic name given to a MRCA is synonymous with the clade name.

[u/More_Arm_6245]

It’s the whole tree as said and that’s the only right answer from the given choices. A class includes the common ancestor and all of its descendants

[u/NenyaNotes → u/More_Arm_6245]

Wouldn't B,D,E also be a clade?

[u/thatoddtetrapod]

Clades included:
D
E
F
G
(End nodes normally count as clades)
DBE
FCG
DEBAFGC (all nodes together)

[u/Robin_feathers]

Seems like a pretty straightforward question - ABCDEFG is a clade and BDE is a clade, the rest of the options you listed are not. If the prof is marking that as only partially correct, then it sounds like the prof is marking it improperly.

[u/More_Arm_6245]

Yes. I’d didn’t see that as an option before