Lichen-forming Fungi DNA

Answer choices

1. A

   Opposite13% picked this

   Evolutionary theorists now postulate that symbiotic interactions generally evolve toward greater parasitism, rather

   We're trying to defend the original assumption that parasitic interactions evolve away from parasitism and toward mutualism (benignity). This answer is saying the opposite. (The author's criticism would weaken this claim, because she would point to the fact that benign and harmful fungus is found both early and late in the evolutionary tree, but this claim doesn't weaken the author's criticism.)

   13%
2. B

   Too Weak6% picked this

   The evolutionary tree of fungi is somewhat more complex than that of similarly parasitic

   This almost gives us a way to say, "Hey, author -- you can't use what's going on with the fungus family tree to dispute this generalization about parasitic relationships because the fungus family tree is an outlier; it's an unrepresentative sample." But we can't get that it's an outlier / unrepresentative sample simply from "somewhat more complex" than other parasitic or symbiotic organisms.

   6%
3. C

   No Impact8% picked this

   The DNA of fungi involved in symbiotic interactions is far more difficult to isolate than that of fungi

   This doesn't have anything to do with the author's criticism (which is about benign and harmful fungi showing up both early and late in the evolutionary timelines of fungi). The fact that the DNA is harder to isolate in one form than the other is a technical hurdle for research scientists. It isn't any sort of commentary on how parasitic fungi evolve.

   8%
4. D

   Strengthens19% picked this

   The placement of lichen-forming fungi as a separate group on the fungus family tree masked the fact that parasitic fungi sometimes evolved

   This reinforces the author's notion that, "Now that we have a cleaned up picture of the fungus family tree (now that the timelines of certain parasitic fungi aren't being masked by being placed in a separate group), we can see that parasitic fungi sometimes evolved much later than symbiotic ones". The assumption the author is fighting is that fungi evolve in this direction: parasitic --------> symbiotic / benign When we see parasitic stuff evolving later than symbiotic stuff, it suggests that the assumption is wrong (and that the author is right).

   19%
5. E

   Correct53% picked this

   Branches of the fungus family tree that have evolved from symbiosis to parasitism usually die

   Why this is right

   This allows us to defend the original assumption that parasitic interactions evolve over time to greater benignity and symbiosis. The author is like, "But wait .... you can find harmful fungi late in the timeline, meaning that some fungi evolved from more benign forms into more parasitic forms". This answer responds, "Yes, but those were evolutionary dead-ends. Just as we expected, it's not a viable long-term strategy to be a harmful parasite. That's why whenever you see a branch of the fungus family tree that 'experimented' with going from being more benign/symbiotic to being more harmful/parasitic, that branch dies out shortly thereafter." Evolution is spurred by mutations, which allows nature to "try out" different survival strategies. This answer is saying that even though you can see the fungus family tree "try out" parasitism early on and later on, it's not a viable road to go down. So maybe in the short term we might see fungus evolve toward more parasitism, since those branches die out shortly thereafter, it still shows that over time we're going to be left with more and more benign interactions, and fewer and fewer parasitic ones.

   Skill tested: Weaken · how this choice captures the passage's function is the move to repeat next time.

   53%