Q6 - The male sage grouse

[sumukh09]

I picked B over D for this one because B strengthened the relationship between courtship and selecting healthy male sage grouse. D only mentions that the symptoms are visible on their air sacs but nothing about how females avoid selecting these male sage grouse because of these symptoms. D on the other does take into account that relationship; during the spring courtship ritual when the male sage grouse inflated these air sacs they were not selected because the females knew that they were diseased presumably because something in the males' air sacs deterred the females away. Why else would they not select only these specific male sage grouse ie) the ones treated with antibiotics?

[tommywallach]

Hey Sumukh,

You know I prefer the top to bottom workout, so let's do it. This is a strengthen, so we start by looking at the core:

Premise: The male grouse shows its inflated air sacs during courtship
Conclusion: This helps females choose healthy mates.

The gap in this argument is fairly straight-forward. Do we know that air sac size/inflation says anything about health?

(A) This would weaken the argument a bit, because it diminishes the necessity of females finding healthy males.

(B) is irrelevant. This wouldn't tell us if the air-sac ritual says anything about health. As for your argument, I think you're being slightly illogical. Courtship, by definition, is the method in which animals choose good partners. You seem to think that we need evidence that sage grouse want healthy partners. If that were true, then (B) would be helpful. But we can take it for granted that females don't want unhealthy males. The question is what air-sacs have to do with that.

(C) would weaken the argument slightly. We want the healthy males to do the air-sac thing, to show off their healthiness.

(D) CORRECT. This would give a reason that showing off air-sacs would convey information about health. Females could see the lack of parasitic infection, meaning the male is a safe bet re: mating.

(E) tells us that the sage can get sick, but it doesn't tell us how that sickness would manifest in terms of their air-sacs. Thus, this is irrelevant to the courtship process.

Hope that helps!

-t

[griffin.811]

Hey Tommy,

When I read A, I marked it as a possible correct answer. My thinking was the fact that some female sage mate with unhealthy grouse shows the need for a way to distinguish between healthy and unhealthy grouse.

Wrong way of thinking?

[tommywallach]

Hey Griffin,

I'm not sure I understand your logic. If females mate with unhealthy grouse, then why would they need to differentiate? The only reason they'd need to differentiate is if they only want to mate with healthy grouse. If they'll mate with healthy or unhealthy grouse, they don't need to distinguish.

Make sense?

-t

[griffin.811]

I see what you mean. I was thinking more along the lines of they do this act, but shouldn't and therefore, need a reason to differentiate this wrong behavior from the correct behavior of mating only with healthy grouse.

For instance, if there were two unmarked trains at a station, and people repeatedly boarded the one headed in the wrong direction, I would think there would be a need for a sign, or some other sort of differentiator.

I think my issue with A is that I assume that the grouse should not mate with unhealthy grouse (because it will weaken the species, and what not).

Thanks again for your response!

[WaltGrace1983]

How does my reasoning look here?

Male displays inflated air sacs to female
→
Ritual is a way for females to select healthy males

The assumption here is that these air sacks actually tell the females something about the health of the male. If they don't then why would we conclude that the air sacks provide the means for females to select healthy males? With this in mind, we go to the questions.

(A) Ok. However, what does this have to do with the ritual? All we are saying here is that there are times when females mate with unhealthy males. However, did they use the ritual? This can be disregarded as an out of scope answer. Also, I like Tommy's point that this may even weaken because it shows that finding a healthy mate isn't that necessary.

(B) I wouldn't necessarily say this is irrelevant. Instead I would say that this weakens the conclusion. Being treated with antibiotics, I think for the purposes of this stimulus, is akin to being healthy. However, this answer choice says that these grouses were not selected, perhaps showing that the ritual isn't about finding a healthy mate. I wouldn't consider this an automatic elimination or anything - this one is tempting - however I would be a bit weary of this too because it doesn't actually attack the gap between the air sacs and how they display healthiness.

(C) This might actually weaken because it shows how some of the healthy males don't even partake in the ritual. If the point of the ritual is to find healthy males and some healthy males don't partake, is the point of the ritual satisfied? I would say no.

(D) This looks much better than (B). It shows this connection between the air sacs and healthiness that we wanted. It says that these air sacs exhibit symptoms of infections. Thus, if during this ritual the grouse had an infection, it would instantly recognizable to the female. This is very good.

(E) I don't see how this is relevant at all. This just says a type of sickness that the grouse might have. Cool - move on.

[LolaC289]

The biggest problem with (B) is that though it talks about unhealthy male sage grouse not being chosen during the courtship rituals, it doesn't mention the specific action of displaying air sacs at all. Since the conclusion is exclusively about "this" courtship ritual (displaying air sacs), we can't tell from (B) which action it is that the females's choice are based on. Maybe they are simply told by the sick physical appearance of the unhealthy males, in that case it would be wholly irrelevant to our argument.

(D) clearly brought up how the displaying of air sacs connect with the health conditions of the males. I did regard it weird because if some unhealthy male will show their unhealthiness when displaying their air sacs, how will they choose to do so, because it seems like diminishing their chance of successful courtship? But now I think I shouldn't be overthinking this because there is no enough information in the stimulus concerning this. Maybe those ill male sage grouse can't check their air sacs by themselves thus do not know that they are sick, in order to court they nevertheless choose to join the displaying army. Or the sage grouse community is female dominated, they have to show whatever the female sage grouse want to check.