Also in 2025 Practice Test B English, question 5.
Passage Excerpt from “It’s Time to Stop Thinking That All Non-Native Species Are Evil”
Excerpt from “It’s Time to Stop Thinking That All Non-Native Species Are Evil”
by Emma Marris
The author of this opinion article attended a symposium, or conference, in Missoula, Montana, at which biologists and other scientists discussed species of plants and animals that are not native to the areas in which they live.
Invasive species are scary. It was ecologist Charles Elton, back in the 1950s, who introduced the militaristic “invasion” metaphor to describe exotic plants and animals—but there’s no question some can be extremely destructive.
The brown tree snake has eaten a dozen kinds of forest birds in Guam to extinction; zebra mussels clog pipes around the Great Lakes; the common house cat turns out to be, in Australia, a mercilessly effective killer of cute, fluffy marsupials like the bilby and the numbat.
As scientists have sounded the alarm about these pests, the public has gotten the message. Citizen groups rip out non-native plants. Native gardens have become increasingly popular, both as ways to celebrate the unique flora of each region and as tiny hot spots of diversity. Native trees provide food for native bugs, which feed native birds. Food chains developed over thousands of years of co-evolution unfold in our backyards. . . .
So we’ve learned, scientists and laypeople alike, that native species are good and non-natives are bad.
Julian Olden, a biologist at the University of Washington, Seattle, who co-organized the symposium, recently polled nearly 2,000 ecologists. Among his findings: a substantial number of them said they would immediately eradicate a hypothetical non-native forest plant, even if it were shown to have no effect on the forest. Olden calls this the “guilty even when proven innocent” approach.
That kind of approach is not very useful on a rapidly changing planet.
Exotics Are Everywhere
Climate change is making it harder even to decide who the invaders are.
How, scientists at the symposium wondered, do you define “native” on a warming planet, when plants and animals are already moving toward the poles or up mountainsides in search of climate conditions they can tolerate? Should we consider them “invasive” in their new homes? Regardless of what we label them, conservationists will be reluctant to remove them from their new environs—to do so would stymie1 their chances of adapting to the warmer future we’re creating.
And then there are the non-natives that we actually like. Most domestic crops are exotic in most of the places they’re grown, but there are even wild exotics that “do good,” forming useful relationships with native species.
Edwin Grosholz of the University of California, Davis, told the recent symposium about one such relationship. On beaches in his state, non-native spartina grass has become important habitat for the endangered California clapper rail, a plump shorebird with a downward curving bill more at home on land than in the air. A project to rip out and poison the spartina—which grows in dense swaths that exclude many other shorebirds—saw clapper rail numbers go tumbling downward.
There are other examples like that. The endangered southwestern willow flycatcher nests in “invasive” tamarisk shrubs. Many native (and beautiful) Hawaiian flowers are now pollinated by the Japanese white-eye bird—because the native pollinators have been driven extinct by other non-native species.
Should we impose further risk on already endangered natives by severing these relationships? Or should we admire the resilience of nature and let such “well-behaved” exotics stay? . . .
Leave them alone, more and more conservationists are arguing, and stop focusing obsessively on categorizing species as native or non-native. Mark Davis, an ecologist at Macalester College in St. Paul, Minnesota, once considered himself an “invasion biologist”—but not anymore. “I am actively trying to get the field to retire the invader narrative,” he said in Missoula.
A Good Thing, Not the Only Thing
After all, nativeness is just one environmental value, and arguably not as important as preventing extinctions and preserving biodiversity. In some cases we can best serve biodiversity by leaving the non-natives alone or even—brace yourself, now—introducing them on purpose.
This is the thinking behind, for example, installing the Aldabra tortoise on the islands of Mauritius. The islands lost their own large tortoises, and the fruiting plants that formerly had their seeds moved around by these fruit-loving reptiles have been on the decline. A tortoise that’s related to the island’s large tortoises—a non-native from the Seychelles in the Indian Ocean that was intentionally introduced in 2004—is now handling some of that work.
Most of the time, for the time being, conserving species still means focusing on supporting them in their historical habitats, planting natives and removing non-natives. We can and should do that in places where it is feasible and important to us.
From “It’s Time to Stop Thinking That All Non-Native Species Are Evil” by Emma Marris from NATIONAL GEOGRAPHIC MAGAZINE, July 24, 2014. Copyright © 2014 by National Geographic Society.
1stymie: hinder or interfere with
Question
The details in the section “A Good Thing, Not the Only Thing” convey a central idea of the excerpt by suggesting that
- Asome non-native species can replace native species that are unable to survive on their own.
- Bdecisions about whether to keep non-native species should be considered on an individual basis.
- Cthe scientists who study rapidly changing ecosystems agree that non-native species enhance biodiversity.
- Da natural habitat that is healthy should be able to support a blend of native and non-native species.
Show the answer
Correct answer: B
The question asks how the details in the section “A Good Thing, Not the Only Thing” convey a central idea of the excerpt.
A. Incorrect. While paragraph 15 does discuss introducing non-native Aldabra tortoises to replace native tortoises that no longer exist, the real point of this section is to show that non-native species can sometimes help support native species that still exist but are struggling. In this case, the Aldabra tortoises are now moving seeds around for the fruiting plants on the islands where the tortoises have been introduced.
B. CORRECT. This section discusses situations in which non-native species should be kept (as in the example of the Aldabra tortoises in paragraph 15) but also asserts that “most of the time . . . conserving species still means focusing on supporting them in their historical habitats, planting natives and removing non-natives” (paragraph 16). This section makes the point that the issue of non-natives needs to be considered on a case-by-case basis.
C. Incorrect. This section does not claim that non-native species always or even usually enhance biodiversity; rather, it states that “in some cases we can best serve biodiversity by leaving the non-natives alone or even—brace yourself, now—introducing them on purpose” (paragraph 14), later adding that “most of the time . . . conserving species still means focusing on supporting them in their historical habitats, planting natives and removing non-natives” (paragraph 16).
D. Incorrect. While the section happens to give a good example of a habitat that supports both native and non-native species (the islands of Mauritius), it never suggests that being able to do so is a defining characteristic of healthy habitats.
Question analysis
This central-idea question asks how the details in the final section of an article on non-native species, titled “A Good Thing, Not the Only Thing,” convey a central idea of the excerpt. Students must sum up the section as a whole, including its example of a tortoise brought to the islands of Mauritius, and match it to the article's larger argument.
- Grade level
- Grade 8 reading and task
- Compared with grade 7
- Above grade 7 Explaining how a section conveys a central idea is grade 7 work, but this section mixes an argument, an example and a closing paragraph, and the choices differ in how far they generalize from it, which demands more than typical.
- Estimated difficulty
- Hard: combines ideas, needs a plan, and has more than one tempting wrong answer.
- Thinking it demands
- Depth of knowledge 3, strategic thinking · mainly understand
- What makes it hard
- The right answer is reworded moderate
- Evidence in several places moderate
- Evidence
- Answered from several paragraphs or stanzas
- Reading level
- Passage: about grade 11, 815 words; question and choices: about grade 11, 82 words.
- Students, last 30 days
- Not enough answers yet to show (it takes 10).
Why it is hard, traps and wrong answers (shows the answer)
Why it is hard
The section's most memorable content is an example, the Aldabra tortoise doing the work of the islands' lost tortoises, and a choice built on it is the strongest pull. The central idea sits instead in the qualifiers at the start and end of the section: some cases favor non-natives, most still call for removing them. Students who summarize all three paragraphs in a sentence, including the last, arrive at the case-by-case reading.
The right answer is reworded moderate Choosing the answer
The right choice's “on an individual basis” appears nowhere in the section, while the wrong choices echo it: a non-native standing in for natives, “biodiversity”, natives alongside non-natives. (Freedle & Kostin, 1993; Kirsch & Mosenthal, 1990)
Evidence in several places moderate Working it out
The case-by-case idea comes only from joining paragraph 14's “In some cases” to paragraph 16's “Most of the time” and “where it is feasible and important to us”. (Kirsch & Mosenthal, 1990; Gorin & Embretson, 2006)
Strategy: Sum up the section's three paragraphs in one sentence of your own, including its example and its final paragraph, then compare that sentence with each choice.
Traps
- Too narrow: A single detail offered as the central idea or a summary, or a summary that keeps minor details and leaves out an essential part.
- Too broad or too strong: A choice overstates, generalizes, or uses absolute words the text does not support.
- Reads too much in: A reasonable-sounding conclusion that goes further than the text allows.
The wrong answers, classified
A Too narrow (King et al., 2004)
Builds on the Aldabra tortoise standing in for Mauritius's lost tortoises, a single example, and misses the closing point that most conservation still means removing non-natives.
C Too broad or too strong (King et al., 2004)
Turns “In some cases” into a consensus that non-natives enhance biodiversity, though the section limits the claim and the article shows ecologists divided over it.
D Reads too much in (Graesser, Singer & Trabasso, 1994)
Draws a rule about healthy habitats from the Mauritius example, though the section never defines a healthy habitat or says it should hold a mix of species.
Working it out, step by step
Know what the question asks
A section is a part of an article under its own heading. This one runs from paragraph 14 to paragraph 16. You need to sum up the whole section, including its last paragraph. Then match that summary to a central idea.
Read paragraph 14
It says that “in some cases” we help nature most “by leaving the non-natives alone.” We might even bring them in “on purpose.” The words “in some cases” are the key. They mean sometimes, not always.
Read the example and the ending
Paragraph 15 gives an example. A non-native tortoise was brought to Mauritius to spread the seeds of fruiting plants. Then paragraph 16 says that “most of the time,” saving species still means “planting natives and removing non-natives.” We should do that “where it is feasible and important to us.” Feasible means possible.
Put the section together
Sometimes it is best to keep a non-native species. Most of the time it is best to remove it. So each case has to be judged on its own. That is what “on an individual basis” means.
Check each choice
- B fits: deciding case by case matches both “in some cases” and “most of the time.”
- A is wrong because the tortoise is one example, and the section ends by saying removal is still the usual choice.
- C is wrong because the section never says scientists agree, and “in some cases” is far from always.
- D is wrong because the section never says what a healthy habitat should hold.
Watch out: A is built on the section’s most memorable detail. But the main idea comes from the words that limit the claim.
Choose the answer
The section says to keep non-natives in some cases and remove them in others. So the answer is B.
Why this answer and not the closest wrong one
A comes closest, because the Aldabra tortoise really does take over work the lost tortoises once did. But that is one case. The section ends by saying that most of the time we still remove non-natives. B covers both sides: some cases call for keeping them, and others call for removing them.
More questions like this
The original DOE question
The passage “Excerpt from “It’s Time to Stop Thinking That All Non-Native Species Are Evil”” as printed (pages 68–70)
