Passage Wolves of the Sea
Wolves of the Sea
The cool and misty landscape of the Great Bear Rainforest can be found along the coast of British Columbia, Canada, and its nearby islands, from Vancouver Island to the Alaskan border. Within this protected area, wolves roam the forests, islands, and beaches. When biologist Chris Darimont began to study these wolves, he wanted to confer with local First Nations groups, as aboriginal Canadians are known, in order to learn what they knew about these wolves. He spoke with Chester Starr, an elder of the Heiltsuk Nation that has occupied the Great Bear Rainforest for thousands of years. What Starr had to say about the wolves changed Darimont’s perception of the animals.
Starr asked Darimont which wolves he and his team were going to study—the timber wolves (mainland wolves) or the coastal wolves on the islands. The question took Darimont by surprise. Biologists had always believed that the wolves that are sometimes spotted swimming between islands and eating salmon are the same wolves that live on the mainland. Darimont was intrigued by Starr’s classification of the wolves as two different groups. At first, he was hesitant to accept the idea. The distances between the mainland and the islands are small, less than a mile. Why would the wolves on the islands be any different from the wolves on the mainland? To find out, Darimont and his research team studied the wolves on the islands and in the densely forested territory of the Great Bear Rainforest for ten years.
Throughout the study, Darimont recorded several significant, observable differences between the “sea wolves,” as they are nicknamed, and the mainland wolves. Compared with the mainland wolves, the sea wolves are smaller in size and are strong swimmers. In 1996 sea wolves were spotted on an island nearly eight miles from any other land formation. While mainland wolves almost exclusively eat meat, such as deer and elk, and teach their young to hunt for land animals, sea wolves get as much as 90 percent of their nutrition from the sea and teach their young to dig for clams and to catch fish. Sea wolves regularly swim between islands and have been known to sneak up on a seal sunning itself on a rock and make a leaping attack from the water. Some salmon-eating mainland wolves come and go from the islands with the fish-spawning season, but the sea wolves are full-time island residents. Darimont suspects that some sea wolves live their entire life on the islands.
The sea wolves displayed not only physical and behavioral differences but also genetic variations from the mainland wolves. After collecting and analyzing the DNA in 800 samples of gray fur and wolf waste, researchers could produce hard biological evidence that sea wolves had genetic markers that made them distinct from the mainland wolves. A genetic marker is a variation in a DNA sequence that can be used to identify individuals or a species because it is passed down to offspring. Darimont hypothesizes that a change in habitat led to the eventual genetic differences between sea wolves and mainland wolves. Many years ago, loss of habitat and food sources forced some mainland wolves out to the islands. They learned to eat everything from kelp and fish eggs to the remains of sea creatures that washed up on the beach. Wolves living on the islands and mainland wolves became more isolated and rarely mated with each other. Over time the two types of wolves became more distinct.
It turned out that Chester Starr was right all along. “It sounded totally bizarre at first,” admits Darimont, “that there could be two versions of the species.” But he now realizes that this skepticism “definitely reflected my ignorance of indigenous knowledge at the time.” Learning to trust the wisdom of the Heiltsuk people opened Darimont up to knowledge accumulated over millennia and positioned him so that he could gather new scientific evidence about one of British Columbia’s most elusive species, the sea wolf.
Question
How did a change in habitat most affect the wolf population of the Great Bear Rainforest over time?
- AIt caused some of the wolves to learn new hunting techniques in order to catch increasingly scarce prey.
- BIt caused the wolves to form smaller packs and eventually separate, establishing distinct territories.
- CIt caused some of the wolves to gradually become a new, genetically distinct species as they adapted behaviorally.
- DIt caused the wolves to adapt their diet as different food sources became available in the area.
Show the answer
Correct answer: C
The question asks how a change in habitat most affected the wolf population of the Great Bear Rainforest over time.
A. Incorrect. Although the island wolves learned new hunting techniques (“dig for clams and to catch fish,” “sneak up on a seal sunning itself on a rock and make a leaping attack from the water” [paragraph 3]), there is no evidence in the passage that these hunting techniques were developed in response to scarcity of prey. The most significant effect of the change in habitat was not an influence on hunting techniques but the behavior differences that evolved because of the isolation of the groups of wolves from each other.
B. Incorrect. The change in habitat did not cause the wolves to form smaller packs but rather served to create distinctive behaviors because of the isolation of one pack from another, eventually causing the groups of wolves to become distinct species.
C. CORRECT. The change in habitat caused the wolves to gradually become two distinct species. Though the “sea wolves regularly swim between islands” and “some salmon-eating mainland wolves come and go from the islands,” the “sea wolves are full-time island residents” (paragraph 3). This behavioral adaptation to their environment caused the sea wolves to become “more isolated” from the mainland wolves; as a result, the two groups “rarely mated with each other,” and “over time the two types of wolves became more distinct” (paragraph 4).
D. Incorrect. Only the sea wolves adapted their diet. They did this not because different food sources became available in the area but because they were in an entirely different area from the mainland wolves.
Question analysis
This cause-and-effect question asks how a change in habitat most affected the wolf population of the Great Bear Rainforest over time, in the article “Wolves of the Sea.” Students must follow the account in paragraphs 3 and 4 of how some wolves came to live on the islands and pick the result the passage treats as the main one, among several that sound possible.
- Grade level
- Grade 7 reading and task
- Compared with grade 7
- At grade 7 Tracing how one event leads to another is core grade 7 informational reading. The effects here are spread over two paragraphs of science writing, and several choices mix real details with causes the passage never gives, which keeps the demand typical.
- Estimated difficulty
- Moderate: several steps, or a close reading with one strong distractor.
- Thinking it demands
- Depth of knowledge 2, skills and concepts · mainly analyze
- What makes it hard
- Evidence in several places moderate
- Reading between the lines minor
- Evidence
- Answered from several paragraphs or stanzas
- Reading level
- Passage: about grade 10, 662 words; question and choices: about grade 10, 85 words.
- Corrected from the DOE handbook
- Two grammar slips in the explanation were corrected.
- 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
Several effects of the move are real, and the strongest wrong answer names one of them, a change of diet, but gives it the wrong cause by having food appear nearby instead of wolves being forced out to the islands. Students who stop at the first effect they recognize miss that the question asks what happened over time. The key’s “new, genetically distinct species” overstates the passage, which calls the wolves “two versions of the species,” though it is still the only choice that follows the chain to its end.
Evidence in several places moderate Working it out
The chain of effects runs across two paragraphs: the island habits of paragraph 3, then paragraph 4’s loss of habitat, isolation, rare mating and the two types becoming “more distinct” over time. (Kirsch & Mosenthal, 1990; Gorin & Embretson, 2006)
Reading between the lines minor Working it out
The word “most” and the phrase “over time” point past the first changes, a new diet and new skills, to the end of the chain, genetic difference, which students must rank as the main effect. (Graesser, Singer & Trabasso, 1994; Kintsch, 1998)
Strategy: Trace the chain of events in paragraphs 3 and 4 from the wolves’ move to the islands onward, then test each choice for who changed, why, and with what result.
Traps
- Twists what the text says: Uses the text's topic and ideas but changes what it says: who did it, how much, when, or why.
- Half right: One half of a two-part choice is right and the other is not.
- Outside knowledge: A choice is plausible in the real world but not supported by this text.
The wrong answers, classified
A Twists what the text says (King et al., 2004)
Joins paragraph 4’s lost food sources to paragraph 3’s new skills, but the scarcity drove wolves to the islands and a new diet, not to new ways of catching scarce prey.
B Outside knowledge (King et al., 2004; Recht & Leslie, 1988)
Supplies familiar facts about wolf packs and territories that the passage never mentions; the groups grew apart because island wolves stayed put and rarely mated with mainland wolves.
D Half right (King et al., 2004; Thissen, Steinberg & Fitzpatrick, 1989)
Rightly sees that diet changed, but only the island wolves changed it, after lost food forced them out, not because new food appeared in the area.
What was corrected from the DOE handbook, and why
- Explanation: The DOE’s explanation of Option B says “eventually causing the groups of wolves to became distinct species”; the site says “to become.” Its explanation of Option C says the change “caused the sea wolves to ‘became more isolated’ from the mainland wolves,” putting paragraph 4’s past-tense “became” after “to”; the site now reads “caused the sea wolves to become ‘more isolated’ from the mainland wolves.”
Working it out, step by step
Figure out what the question asks
This is a cause-and-effect question. The cause is a change in habitat. A habitat is the place where an animal lives and finds food. You need the biggest effect it had “over time.” So follow the whole chain of events to its end.
Find the cause in paragraph 4
Paragraph 4 says, “Many years ago, loss of habitat and food sources forced some mainland wolves out to the islands.” There, “They learned to eat everything from kelp and fish eggs to the remains of sea creatures that washed up on the beach.” Kelp is a kind of seaweed.
Follow the chain to its end
Next, the two groups “became more isolated and rarely mated with each other.” Isolated means cut off. Then, “Over time the two types of wolves became more distinct.” Distinct means clearly different. Darimont thinks the change in habitat “led to the eventual genetic differences.” Genetic means in the DNA, passed from parents to young. So the chain ends with the two groups becoming different in their DNA.
Check each choice
- A is wrong. Lost food sent wolves to the islands. The passage never says they learned tricks to catch scarce, or hard-to-find, prey.
- B is wrong. The passage never mentions packs or territories.
- C is right. Some wolves changed how they live, then grew apart in their DNA. One caution: C says “species.” The passage is more careful. It speaks of “two versions of the species.”
- D is wrong. Only the island wolves changed their diet. They did not find new food nearby. Lost food forced them to move.
Watch out: D names a real effect, a new diet. But that is only an early step, and D gives the wrong reason for it.
Choose the answer
The biggest effect over time was that the island wolves grew different in their DNA from the mainland wolves. So the answer is C, “It caused some of the wolves to gradually become a new, genetically distinct species as they adapted behaviorally.”
Why this answer and not the closest wrong one
D is the closest wrong answer, because the diet really did change. But D says new food “became available in the area.” The passage says the opposite: lost food forced some wolves out to the islands. A new diet is also only an early step. C follows the chain all the way to the change in their DNA.
More questions like this
The original DOE question
The passage “Wolves of the Sea” as printed (pages 23–24)
