雅思阅读真题+题目+答案：Charles Darwin’s theory and Finches

雅思阅读真题+题目+答案：Charles Darwin’s theory and Finches

A

Today, the quest continues. On Daphne Major- one of the most desolate of the Galapagos 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 good . Biologist 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 Gal a pagos 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 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(v.偷吃，毀灭)the last of the small, easily eaten seeds. Smaller members of the medium ground finch population, lack 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 Galapagos’ 14 unique finch species, all descended from a common ancestor that reached the islands a few million years ago.

E

Eight years later(1985), heavy rains brought by an El Nino transformed the normally meager vegetation on Daphne Major. 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 happens when the environment changes. When local conditions reverse themselves, so does the direction of adaptation.’

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雅思阅读真题题目：

Question 1-8

Complete the table below.

Choose NO MORE THAN TWO WORDS from Reading Passage 1 for each answer. Write your answers in boxes 1-8 on your answer sheet.

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