PT104.S2.P3.Q17 > Analytics

Hide analysis

Many birds that form flocks compete through aggressive interaction for priority of access to resources such as food and shelter. ███ ██████ ██ ████████ ████████████ ███████ █████ ███████ ██ ████ ████ ████ █████ █ ██████████ ██████ ██████ ███████ ██ ███ ████████ ████████ ████ ████████ ██ ██████ ██ █████████ ██████████ ████ ██████ ███████ ███

Phenomenon · Status hierarchy in birds

Top bird has best fighting ability which grants them first dibs on food and shelter. Then next bird get their turn, then next, and so on. Each bird has a position on this status hierarchy.

██ ███ ██████ ███ █████████ ██ ████████████ ███████ █████ █████████ ████████ ██ ████████ ███ █████ ██ ████ ████ ██ █████ ██ ██████ ████████████ █████ ███ ████ ██ ███████ ███

Negative Consequence · Maintaining social status is costly: energy, time, and risk of injury

Hypothesis · Status signaling hypothesis (SSH)

Instead of actually fighting to establish social status, birds can instead signal their fighting ability and thereby not have to risk actually getting hurt. A bird's plumage is one such signal of fighting ability.

Rohwer · Sparrow plumage supports SSH

Birds with darker throats win conflicts against birds with lighter plumage, controlling for age and sex.

████████ ████████ ████ ██ ███ ███████ ███ ███████████ ██ ███ ██ ███ ███████ ██████ █████ ███ ████ ██ ███ ██ ██ ██████████ ██████ ████████ ████████ ██ █████████ ███████ █████ ██ ███ ████ ███ █████ ██ ████ ██████ █████ ███ ██ ███ ████ ███ █████ ███ ███████████ ████ ███████ ████████ ████ ██████ █████ ███████████ ███████████ ██ ██████ █████ ██████ █████████ ███████ ███████ ████ █████████ ████ ██████ ██████ ████ ██████████ ███ ███ ███████ █████ █████████ █████████ █████████ ████ ██ ████████ ██████ ███ ████████ ████ ██████ ██████████ ████████ ███ ██████ █████████ ███████████ ███████ ███████████ ██ ███ ██████ ███ ██████ ██ ██████████ █████ ██████ ██ ███ ██████ ███ ████ ██████ ████████ ██ ████████ █████ ███ ████ █████████ █████████████

Critique of Rohwer · Data doesn't support his claims

Darker plumage birds don't always win conflicts. Also, age is actually a confounder. Age is a signal of status and plumage just happens to darken with age. Hence, plumage is not a status signal for these sparrows.

Experimental Evidence for SSH · Greater titmouse

Width of black breast-plumage stripe signals status. Experiment controlled for sex, age, wing length, and body weight.

██ █████████ ██████████ ████████ ███████ ████████ ███ ██████ █████████ ██ ███ ███████ █████████ ███ ██ █████ ███████ ████████ ███████ ███ ███████ ██ █ ███████ █████ ████ █ ████ ████ ███████████ ███ █████ ███ ██████ ██ █████ ███████ ██ ████ ███ ████ ███ ███████ ███ ██████ ██████ ██ ██████████████ ████ █████████ ████ █ █████ ██████ █ ████████ ██████ ██████ ████ █████ ████ █████ ██████████ ███████ ███ ███████ █████████████ ████████ ████ █████████ ████ █ █████ ██████ █ ███████ ██████ ██████ ████ █████ ████ ████ █████ █████ ██████████ ███ ███ ███ █████████

Experimental Evidence for SSH · Greater titmouse

Stuffed titmouse dummies with narrower v. broader breast stripes caused other birds to behave aggressively v. submissively, as predicted by SSH.

Passage Style

Critique or debate

Phenomenon-hypothesis (RC)

17.

Which one of the following, ██ █████ █████ ████ █████████ █████████ ███ ████████ ██ ███ ███████ ██ ███ ██████████ █████████ ██ ███ ████ ██████████

Question Type

WSE (RC)

We can undermine the validity of the results by providing evidence that the difference in breast stripe width might not explain the birds’ different reactions to the dummies. Is there some other reason the birds might have acted more or less aggressively to different models?

The live birds ███ ████ ████ █████████ ████████ ███████

If anything, this might strengthen the validity of the experiment by showing that the reactions differed based on stripe width regardless of which flock the birds came from.

The physical characteristics ██ ███ ███████ ███████ ██████ ██ ████ █████ ████ ████ █████████████ ██████

This weakens by providing a potential alternate explanation for the birds’ differing reactions. Maybe the birds were reacting to some other differences in physical characteristics of the dummies, and not to breast stripe width.

90%

No live juvenile █████ ████ ████████ ██ ███ ███████████

We have no reason to think the lack of inclusion of young birds has any impact on the results of the experiment.

The food placed ██ ███ ███████ ████ ███ ███ ███ ████ ██ ████ ████████ █████ ██ ███████ ██ ███ █████

(D) doesn’t suggest that different foods were used with different dummies, so it doesn’t present an alternate explanation for the birds’ reactions.

Even the live █████ ████ █████ ████████████ ███ ███ ████████ ██████████ ██████ ███ ███████ ████████

We have no reason to think the lack of physical attacks affects the results of the experiment. We still observed different levels of aggression to different dummies.

PrepTest 104 - Section 2 - Passage 3 - Question 17

Difficulty

Analysis

Answer Popularity

Question history

Confirm action