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 author’s use of cause and effect in paragraphs 10–11 mainly emphasizes the idea that
- Asome non-native species have helped their environments while others have had harmful impacts.
- Battempts to remove non-native species have seldom produced desired results.
- Csome endangered native species have flourished because of the presence of non-native species.
- Dinteractions between endangered native species and non-native species must be carefully monitored.
Show the answer
Correct answer: C
The question asks what the author’s use of cause and effect in paragraphs 10–11 mainly emphasizes.
A. Incorrect. The examples of cause and effect discussed in paragraphs 10–11, such as the spartina grass helping the clapper rail and the Japanese white-eye bird pollinating Hawaiian flowers, are all instances in which non-native species have helped their new environments.
B. Incorrect. While paragraph 10 does mention that efforts to eradicate the non-native spartina grass hurt the native clapper rail shorebird, the main emphasis in both paragraphs 10–11 is on the fact that certain non-native species have helped native species.
C. CORRECT. Paragraphs 10–11 focus on several examples of non-native species that have helped endangered native species flourish: non-native spartina grass providing “important habitat for the endangered California clapper rail” (paragraph 10), non-native tamarisk shrubs providing nesting places for the endangered southwestern willow flycatcher (paragraph 11), and the non-native Japanese white-eye bird pollinating Hawaiian flowers (paragraph 11).
D. Incorrect. While paragraphs 10–11 describe several interactions between non-native and native species, they never discuss monitoring these interactions.
Question analysis
This text-structure question asks what the cause-and-effect examples in two paragraphs of an article about non-native species mainly emphasize. The paragraphs describe a shorebird, a flycatcher and Hawaiian flowers, and students must decide what the examples have in common rather than fixing on any one of them.
- Grade level
- Grade 8 reading and task
- Compared with grade 7
- Above grade 7 Analyzing what a cause-and-effect structure emphasizes is grade 7 work, but these examples involve unfamiliar species and endangered status, and more than one choice is partly supported by the paragraphs, which raises the demand above 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 analyze
- What makes it hard
- A very close wrong answer major
- Reading between the lines moderate
- An unfamiliar subject minor
- Evidence
- Answered from several paragraphs or stanzas
- Reading level
- Passage: about grade 11, 815 words; question and choices: about grade 11, 62 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 paragraphs mention harm as well as help, so a balanced statement about both looks accurate and even fair-minded. What the cause-and-effect pairs stress, though, is endangered natives depending on non-natives, and the right answer captures that while overstating it, since a bird whose numbers held up only with spartina's help can hardly be said to have flourished. Students must prefer the statement of the main emphasis to one that is partly supported but off the point.
A very close wrong answer major Choosing the answer
The right choice and the help-and-harm choice both say non-natives have aided their surroundings; they part on harm, which the paragraphs do mention, spartina crowding out shorebirds and other non-natives killing Hawaii's pollinators, but only in passing. (Embretson & Wetzel, 1987; Gorin & Embretson, 2006; Ascalon et al., 2007)
Reading between the lines moderate Working it out
Paragraph 10 states its cause and effect backwards, removing spartina sent clapper rail numbers “tumbling downward”, and the student must turn that around into the grass's presence helping the bird. (Graesser, Singer & Trabasso, 1994; Kintsch, 1998)
An unfamiliar subject minor Understanding the question
Five unfamiliar species crowd two paragraphs, spartina grass, the California clapper rail, tamarisk shrubs, the southwestern willow flycatcher and the Japanese white-eye, and each one's role must be kept straight. (Recht & Leslie, 1988; Kintsch, 1998)
Strategy: List each cause-and-effect pair in paragraphs 10 and 11, the species involved and what happened to them, then pick the statement that holds for the examples taken together.
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.
- Outside knowledge: A choice is plausible in the real world but not supported by this text.
The wrong answers, classified
A Too narrow (King et al., 2004)
Accurately notes helpful and harmful non-natives, but the harm is mentioned only in passing, and it leaves out what every example stresses, endangered natives depending on non-natives.
B Too broad or too strong (King et al., 2004)
Generalizes from the single spartina project in paragraph 10 to removal attempts in general, a “seldom” claim that neither paragraph makes.
D Outside knowledge (King et al., 2004; Recht & Leslie, 1988)
Adds a sensible-sounding call for careful monitoring, the kind of advice scientists often give, but neither paragraph says anything about watching over these relationships.
Working it out, step by step
Know what the question asks
In a cause-and-effect pattern, one thing makes another happen. You need the main idea that the causes and effects in paragraphs 10 and 11 stress. Start by listing each pair.
List each cause and effect
- Paragraph 10: non-native spartina grass gives the endangered clapper rail a home, so when people ripped out the grass, clapper rail numbers went “tumbling downward.”
- Paragraph 11: the endangered willow flycatcher nests in non-native tamarisk shrubs.
- Paragraph 11: native Hawaiian flowers are now pollinated by a non-native bird, the Japanese white-eye.
Find the common thread
Endangered means at risk of dying out. Pollinated means a bird or bug carries pollen between flowers so they can make seeds. In every pair, a native species depends on a non-native one. The newcomer gives it a home, a place to nest or a pollinator. Two of the natives, the clapper rail and the flycatcher, are endangered. So the paragraphs stress that some endangered natives do better because non-natives are there.
Check each choice
- C fits: some endangered natives have “flourished,” or done well, because non-natives are present.
- A is wrong because harm comes up only in passing, while every example stresses a native getting help.
- B is wrong because one removal project is not enough to say removal “seldom” works.
- D is wrong because the paragraphs never mention monitoring, or watching over, these relationships.
Watch out: The paragraphs do mention harm. Spartina crowds out some other shorebirds, and other non-natives wiped out Hawaii’s native pollinators. So A sounds balanced, but it misses the main point.
Choose the answer
The causes and effects show struggling natives, two of them endangered, helped by non-natives. So the answer is C.
Why this answer and not the closest wrong one
A comes closest, because the paragraphs mention harm as well as help. But the harm is only a side note. Every cause and effect shows a native relying on a non-native, and two of those natives are endangered birds. C names that main point, even though “flourished” is a strong word for birds that are still endangered.
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)
