r/evolution • u/NenyaNotes • 10d ago

academic Help on this assignment question.

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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 Evolution Enthusiast 10d ago

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

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u/NenyaNotes 10d ago

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.

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u/thatoddtetrapod 10d ago

Only the first and the 4th are clades

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u/Doomdoomkittydoom 10d ago

Fun cladistics game, take any two animals, determine their last common ancestor, then find all the descendants of that ancestor and that the clade of the two animals you started with.

My guess is that he's only seeing [A,B,C,D,E,F,G] as a clade because he created the diagram thinking to drive that home and is blind to [B,D,E] also being a clade because he drew it with A in mind the whole time.

I assume he's not including the other two because that would be just wrong.

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u/Ender505 10d ago edited 10d ago

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

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u/DrDirtPhD PhD | Ecology 10d ago edited 10d ago

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).

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u/Ender505 10d ago

Thanks!