Self-study
Ecologist: Before finding a mate, male starlings decorate their nests with fragments of aromatic plants rich in compounds known to kill parasitic insects. █████ █████ █████████ ███ ███████████ ███████ ██ ██████████ ████ ███████████ ████ ████████████ ████ ███ ████████ ██ █████ ███████████ ██ ████████ ███████████ ████████ █████ █████ ██ ███████████ ████ ████████ ████ ███ ██████ ███████ █████ ████████ ███████ ████ ███ ████████ ██ ███ ███████████ ██ ██ ███████ ████████
Summarize Argument: Phenomenon-Hypothesis
The ecologist hypothesizes that the reason male starlings use aromatic plants in their nests is to attract females, contrary to previous hypotheses that the plants protected nestlings from parasites. This is based on the observation that these males only incorporate these aromatic plants before egg-laying begins, and stop adding them to nests when egg-laying begins.
Notable Assumptions
The ecologist assumes that there is not an alternate explanation for the male starlings only incorporating the aromatic plants before egg-laying.
The ecologist also assumes that aromatic plants incorporated before egg-laying couldn’t kill parasitic insects over an extended time period, and thus still protect nestlings.
4.
Which one of the following, ██ █████ ████ ███████████ ███ ███████ ███ ███ ███████████ ███████████
a
Adult starlings are ████ ██ ██████ ██████████ ███████ █████████ ████████
This is irrelevant, since the effect of parasitic insects on adults is not discussed in the argument. We only care about parasites’ potential harmful effect on nestlings and whether the aromatic plants function to counteract that harm.
b
Male starlings do ███ ████████ █████ █████ ██ █████ ████ █████████ █████ ███████████ ██ █████████ ████████
This weakens by providing more evidence that these decorations do have to do with parasitic insects after all, if they are only used in nests in areas where parasitic insects are a threat.
Directionally wrong
Directionally wrong
Answers that, if they have any effect, do the opposite of what we want (weaken when we're trying to strengthen, or strengthen when we're trying to weaken).
c
Nestlings grow faster ██ █████ ████ ███████████ ████████ ██████ ████ ██ █████ ████ ██ ████
This seems to weaken by suggesting an alternate explanation for the incorporation of aromatic plants in nests: to help nestlings grow faster. It’s still not clear whether it makes a difference when the decoration occurs, but this certainly doesn’t strengthen.
Directionally wrong
Directionally wrong
Answers that, if they have any effect, do the opposite of what we want (weaken when we're trying to strengthen, or strengthen when we're trying to weaken).
d
Male starlings tend ██ ████████ █████ █████ ████ █ ███████ ██████ ██ ████████ ██████ ████ █ █████ ██████ ██ ██████████ ████████ ██ ███ █████
This strengthens by providing direct evidence in support of the ecologist’s hypothesis: males increasing the use of aromatic plants when females are nearby is consistent with those plants functioning to attract females.
Plausibility
Plausibility
Presenting evidence that corroborates (in Strengthen) or conflicts (in Weaken) with the author's hypothesized explanation or the predictions that follow from that explanation.
e
The compounds in ███ ████████ ██████ ████ ██ ███ ████ █████████ ██ ████████ █████ █████ ███ ████████ ██ ██████████
This doesn’t affect the ecologist’s hypothesis, since the argument has nothing to do with whether the aromatic plants are harmful to nestlings.