Table of Contents
Finches on Islands
Passage
A. Today, the quest continues. On Daphne Major —one of the most desolate of the Galápagos Islands, an uninhabited volcanic cone where cacti and shrubs seldom grow higher than a researcher’s knee Peter and Rosemary Grant have spent more than three decades watching Darwin’s finches respond to the challenges of storms, drought and competition for food. Biologists at Princeton University, the Grants know and recognize many of the individual birds on the island and can trace the birds’ lineages back through time. They have witnessed Darwin’s principle in action again and again, over many generations of finches.
B. The Grants’ most dramatic insights have come from watching the evolving bill of the medium ground finch. The plumage of this sparrow-sized bird ranges from dull brown to jet black. At first glance, it may not seem particularly striking, but among scientists who study evolutionary biology, the medium ground finch is a superstar. Its bill is a middling example in the array of shapes and sizes found among Galapagos finches: heftier than that of the small ground finch, which specializes in eating small, soft seeds, but petite compared to that of the large ground finch, an expert at cracking and devouring big, hard seeds.
C. When the Grants began their study in the 1970s, only two species of finch lived on Daphne Major, the medium ground finch and the cactus finch. The island is so small that the researchers were able to count and catalogue every bird. When a severe drought hit in 1977, the birds soon devoured the last of the small, easily eaten seeds. Smaller members of the medium ground finch population, lacking the bill strength to crack large seeds, died out.
D. Bill and body size are inherited traits, and the next generation had a high proportion of big-billed Individuals. The Grants had documented natural selection at work the same process that over many millennia, directed the evolution of the Galápagos’ 14 unique finch species, all descended from a common ancestor that readied the islands a few million years ago.
E. Eight years later, heavy rains brought by an El Nino transformed the normally meager vegetation on Daphne Ma ị or. vines and other plants that in most years struggle for survival suddenly flourished, choking out the plants that provide large seeds to the finches. Small seeds came to dominate the food supply, and big birds with big bills died out at a higher rate than smaller ones. ‘Natural selection is observable/ Rosemary Grant says. ‘It happen when the environment changes. When local conditions reverse themselves, so does the direction of adaptation.’
F. Recently, die Grants witnessed another form of natural selection acting on the medium ground finch: competition from bigger, stronger cousins. In 1982, a third finch, the large ground finch, came to live on Daphne Major. The stout bills of these birds resemble the business end of a crescent wrench. Their arrival was the first such colonization recorded on the Galapagos in nearly a century of scientific observation. ‘We realized,’ Peter Grant says, ‘we had a very unusual and potentially important event to follow/ For 20 years, the large ground finch coexisted with the medium ground finch, which shared five supply of large seeds with its bigger-billed relative. Then, in 2002 and 2003, another drought struck. None of the birds nested that year, and many died out. Medium ground finches with large bills, crowded out of feeding areas by the more powerful large ground finches, were hit particularly hard.
G. When wetter weather returned in 2004, and the finches nested again, the new generation of the medium ground finch was dominated by smaller birds with smaller bills, able to survive on smaller seeds. This situation, says Peter Grant, marked the first time that biologists have been able to follow the complete process of an evolutionary change due to competition between, species and the strongest response to natural selection that he had seen in 33 years of tracking Galapagos finches.
H. On the inhabited island of Santa Cruz, just south of Daphne Major, Andrew Hendry of McGill University and Jeffrey Podos of the University of Massachusetts at Amherst have discovered a new, man-made twist in finch evolution. Their study focused on birds living near the Academy Bay research station, on the fringe of the town of Puerto Ayora. The human population of the area has been growing fast—from 900 people in 1974 to 9,582 In 2001. Today Puerto Ayorn is full of hotels and mai tai bars,’ Hendry says. ‘People have taken tills extremely arid place and tried to turn it Into a Caribbean resort.
I. Academy Bay records dating back to the early 1960s show that medium ground finches captured there had either small or large bills. Very few of the birds had mid-size bills. The finches appeared to be In the early stages of a new adaptive radiation: If the trend continued, the medium ground finch on Santa Cruz could split Into two distinct subspecies, specializing in different types of seeds. But in the late 1960s and early 70s, medium ground finches with medium-sized bills began to thrive at Academy Bay along with small and large- billed birds. The booming human population had introduced new food sources, including exotic plants and bird feeding stations stocked with rice. Billsize, once critical to the fishes’ survival, no longer made any difference. ‘Now an intermediate bill can do fine/ Hendry says.
J. At a control site distant from Puerto Ayora, and relatively untouched by humane, the medium ground finch population remains split between large- and small-billed birds. On undisturbed parts of Santa Cruz, there Is no ecological niche for a middling medium ground finch, and the birds continue to diversify. In town, though there are still many finches, once-distinct populations are merging.
K. The finches of Santa Cruz demonstrate a subtle process in which human meddling can stop evolution In Its tracks, outing the formation of new species. In a time when global biodiversity continues Its downhill slide, Darwin’s finches have yet another unexpected lesson to teach. ‘If we hope to regain some of the diversity that’s already been lost/ Hendry says, ‘we need to protect not just existing creatures, but also the processes that drive the origin of new species.’
Questions
Questions 1-4
Complete the table below.
| Year | Climate | Finch’s condition |
| 1977 | 1…………. | small-beak birds failing to survive, |
| without the power to open 2…………. | ||
| 1985 | 3 ………. brought | big-beak birds dying out, with |
| by El Nino | 4………as the main food resource |
Questions 5-8
Choose NO MORE THAN TWO WORDS from Reading Passage 1 for each answer. Write your answers in boxes 1-4 on your answer sheet.
Write your answers in boxes 5-8 on your answer sheet
On the remote island of Santa Cruz, Andrew Hendry and Jeffrey Podos conducted a study on reversal 5………….due to human activity. In the early 1960s medium ground finches were found to have a larger or smaller beak. But in the late 1960b and early 70s, finches with 6………….flourished. The study speculates that it is due to the growing 7……………who brought in alien plants with intermediate-size seeds into the area and the birds ate 8…………….. sometimes.
Questions 9-13
Do die following statements agree with the information given in Reading Passage 1?
In boxes 9-13 on your answer sheet, write
TRUE if the statement is true
FALSE if the statement is false
NOT GIVEN if the information is not given in the passage 1
9. Grants’ discovery has questioned Darwin’s theory.
10. The cactus finches are less affected by food than the medium ground
11. finch- In 2002 and 2003, all the birds were affected by the drought
12. The discovery of Andrew Hendry and Jeffrey Podos was the same as that of the previous studies.
13. It is shown that the revolution in finches on Santa Cruz is likely a response to human intervention.
Answers
Below are the answers, key words, synonyms and full explanations for the IELTS Reading passage Finches on Islands (Passage 1, Questions 1–13).
Questions 1–4: Table Completion (NO MORE THAN TWO WORDS)
1. 1977 climate: ______
Answer: drought
Key words: When a severe drought hit in 1977, the birds soon devoured the last of the small, easily eaten seeds
Explanation: 1977 saw a severe drought → drought.
2. small-beak birds failing to survive, without the power to open ______
Answer: large seeds
Key words: Smaller members of the medium ground finch population, lacking the bill strength to crack large seeds, died out
Synonyms: without the power to open ______ = lacking the strength to crack large seeds = “lacking the bill strength to crack large seeds”
Explanation: Small-billed birds could not open large seeds → large seeds.
3. 1985 climate: ______ brought by El Nino
Answer: heavy rains
Key words: Eight years later, heavy rains brought by an El Nino transformed the normally meager vegetation
Explanation: El Niño brought heavy rains → heavy rains.
4. big-beak birds dying out, with ______ as the main food resource
Answer: small seeds
Key words: Small seeds came to dominate the food supply, and big birds with big bills died out at a higher rate
Synonyms: main food resource = small seeds dominating the food supply = “Small seeds came to dominate the food supply”
Explanation: Small seeds dominated, hurting big-billed birds → small seeds.
Questions 5–8: Summary Completion (NO MORE THAN TWO WORDS)
5. Hendry and Podos conducted a study on reversal ______ due to human activity.
Answer: finch evolution
Key words: Andrew Hendry … and Jeffrey Podos … have discovered a new, man-made twist in finch evolution
Explanation: Their study concerned finch evolution → finch evolution.
6. in the late 1960s and early 70s, finches with ______ flourished.
Answer: medium-sized bills
Key words: medium ground finches with medium-sized bills began to thrive at Academy Bay
Explanation: Medium-billed finches thrived → medium-sized bills.
7. it is due to the growing ______ who brought in alien plants.
Answer: human population
Key words: The booming human population had introduced new food sources, including exotic plants
Synonyms: the growing ______ = the booming human population = “The booming human population had introduced new food sources”
Explanation: The growing human population introduced new plants → human population.
8. the birds ate ______ sometimes.
Answer: rice
Key words: bird feeding stations stocked with rice
Explanation: Feeding stations offered rice → rice.
Questions 9–13: True / False / Not Given
9. Grants’ discovery has questioned Darwin’s theory.
Answer: FALSE
Key words: They have witnessed Darwin’s principle in action again and again … The Grants had documented natural selection at work
Synonyms: questioned Darwin’s theory (contradicted) = they confirmed Darwin’s principle repeatedly = “They have witnessed Darwin’s principle in action again and again”
Explanation: Their work confirms, not questions, Darwin → FALSE.
10. The cactus finches are less affected by food than the medium ground finch.
Answer: NOT GIVEN
Key words: (the passage names the cactus finch but never compares how food affects it versus the medium ground finch)
Explanation: No such comparison is made → NOT GIVEN.
11. In 2002 and 2003, all the birds were affected by the drought.
Answer: TRUE
Key words: in 2002 and 2003, another drought struck. None of the birds nested that year, and many died out
Synonyms: all the birds were affected = none nested and many died = “None of the birds nested that year, and many died out”
Explanation: None nested and many died — all were affected → TRUE.
12. The discovery of Andrew Hendry and Jeffrey Podos was the same as that of the previous studies.
Answer: FALSE
Key words: have discovered a new, man-made twist in finch evolution
Synonyms: same as previous studies (contradicted) = a NEW, man-made twist = “a new, man-made twist in finch evolution”
Explanation: Their finding was new (human-caused), not the same as before → FALSE.
13. It is shown that the evolution in finches on Santa Cruz is likely a response to human intervention.
Answer: TRUE
Key words: The finches of Santa Cruz demonstrate a subtle process in which human meddling can stop evolution in its tracks
Synonyms: a response to human intervention = human meddling affecting evolution = “human meddling can stop evolution in its tracks”
Explanation: The Santa Cruz change is driven by human intervention → TRUE.
Answer Key (Quick Reference)
| Q | Answer | Q | Answer |
|---|---|---|---|
| 1 | drought | 8 | rice |
| 2 | large seeds | 9 | FALSE |
| 3 | heavy rains | 10 | NOT GIVEN |
| 4 | small seeds | 11 | TRUE |
| 5 | finch evolution | 12 | FALSE |
| 6 | medium-sized bills | 13 | TRUE |
| 7 | human population |
