雅思考试阅读常见题材-12植物origin of species

Origin of Species & Continent FormationA The fact that there was once a Pangean supercontinent, a Panthalassa

Ocean, and a Tethys Ocean, has profound implications for the evolution

of multicellular life on Earth. These considerations were unknown to the

scientists of the 19th century—making their scientific deductions even more

remarkable. Quite independently of each other, Charles Darwin and his

young contemporary Alfred Russel Wallace reached the conclusion that life

had evolved by natural selection. Wallace later wrote in My Life of his own

inspiration:B Why do some species die and some live? The answer was clearly that on

the whole the best fitted lived. From the effects of disease the most healthy

escaped;from enemies the strongest, the swiftest or the most cunning from

famine the best hunters…then it suddenly flashed on me that this self-acting

process would improve the race, because in every generation the inferior

would inevitably be killed off and the superior would remain, that is , the

fittest

would survive.C Both Darwin’s and Wallace’s ideas about natural selection had been influenced

by the essays of Thomas Malthus in his Principles of Population. Their

conclusions, however, had been the direct result of their personal observation

of animals and plants in widely separated geographic locations:Darwin from

his experiences during the voyage of the Beagle, and particularly during the

ship’s visit to the Galapagos Islands in the East Pacific in 1835; Wallace during

his years of travel in the Amazon Basin and

in the Indonesia-Australian Archipelago in

the 1850s.

D Darwin had been documenting his ideas on

natural selection for many years when he

received a paper on this selfsame subject

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from Wallace, who asked for Darwin’s opinion and help in getting it published.

In July 1858, Charles Lyell and J. D Hooker, close friends of Darwin, pressed

Darwin to present his conclusions so that he would not lose priority to

and unknown naturalist. Presiding over the hastily called but now historic

meeting of the Linnean Society in London, Lyell and Hooker explained to the

distinguished members how

“these two gentlemen” (who were absent:Wallace

was abroad and Darwin chose not to attend), had

“independently and unknown

to one another, conceived the same very ingenious theory,

”B oth Darwin and Wallace had realized that the anomalous distribution

of species in particular regions had profound evolutionary significance.

Subsequently, Darwin spent the rest of his days in almost total seclusion

thinking and writing mainly about the origin of species. In contrast, Wallace

applied himself to the science of biogeography, the study of the pattern and

distribution of species, and its significance, resulting in the publication of a

massive two-volume work the Geographical Distribution of Animals in 1876.W allace was a gentle and modest man, but also persistent and quietly

courageous. He spent years working in the most arduous possible climates and

terrains, particularly in the Malay archipelago, he made patient and detailed

zoological observations and collected huge number of specimens for museums

and collectors-which is how he made a living. One result of his work was

the conclusion that there is a distinct faunal boundary, called

“Wallace’s line,

“between an Asian realm of animals in Java, Borneo and the Philipiones and

an Australian realm in New Guinea and Australia. In essence this boundary

posed a difficult question: How on Earth did plants and animals with a clear

affinity to the Northern Hemisphere meet with their Southern Hemispheric

counterparts along such a distinct Malaysian demarcation zone? Wallace was

uncertain about demarcation on one particular island-Celebes, a curiously

shaped place that is midway between the two groups. Initially he assigned its

flora-fauna to the Australian side of the line, but later he transferred it to the

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Asian side. Today we know the reason for his dilemma. 200MYA East and

West Celebes were islands with their own natural history lying on opposite

sides of the Tethys Ocean. They did not collide until about 15 MYA. The

answer to the main question is that Wallace’s Line categorizes Laurasia-derived flora-fauna (the Asian) and Gondwana-derived flora-fauna (the

Australian), fauna that had evolved on opposing shares of the Tethys. The

closure of the Tethys Ocean today is manifested by the ongoing collision of

Australia/New Guinea with Indochina/Indonesia and the continuing closure of

the Mediterranean Sea—a remnant of the Western Tethys Ocean.

G In his origin of continents and oceans, Wegener quoted at length from

Wallace’s Geographical Distribution of Animals. According to Wegener’s

reading, Wallace had identified three clear divisions of Australian animals,

which supported his own theory of continental displacement. Wallace had

shown that animals long established in southwestern Australia had an affinity

with animals in South Africa, Madagascar, India, and Ceylon, but did not have

an affinity with those in Asia. Wallace also showed that Australian marsupials

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and monotremes are clearly related to

those in South America, the Moluccas,

and various Pacific islands, and that none

are found in neighboring Indonesia. From

this and related data, Wegener concluded that the then broadly accepted

“landbridge” theory could not account for this distribution of animals and that

only his theory of continental drift could explain it.

T he theory that Wegener dismissed in preference to his own proposed that

plants and animals had once migrated across now-submerged intercontinental

landbridges. In 1885, one of Europe’ s leading geologists, Eduard Suess,

theorized that as the rigid Earth cools, its upper crust shrinks and wrinkles like

the withering skin of an aging apple. He suggested that the planet’s seas and

oceans now fill the wrinkles between once-contiguous plateaus.T oday, we know that we live on a dynamic Earth with shifting, colliding and

separating tectonic plates, not a

“withering skin”, and the main debate in the

field of biogeography has shifted. The discussion now concerns

“ dispersalism”

versus

“vicarianism: unrestricted radiation of species on the one hand and the

development of barriers to migration on the other. Dispersion is a short-term

phenomenon—the daily or seasonal migration of species and their radiation

to the limits of their natural environment on an extensive and continuous

landmass. Vicarian evolution, however, depends upon the separation and

isolation of a variety of species within the confines of natural barriers in the

form of islands, lakes, or shallow seas—topographical features that take a long

time to develop.63

Questions 1-5

.................................................................................Use the information in the passage to match the people (listed A-E) with opinions or

deeds below. Write the appropriate letters A-E in boxes 1-5 on your answer you may use any letter more than onceA

B

C

D

E

1

2

3

4

5

SuessWallaceDarwin and WallaceWegenerLyell and HookerPersuade Darwin to publish his scientific findingsDepicted physical feature of earth’s uced continental drift hed works about wildlife distribution in different ion of species is based on selection by ons 6-8

.................................................................................The reading Passage has nine paragraphs paragraph contains the following information?Write the correct letter A-I, in boxes 6-8 on your answer sheet.6

7

8

Best adaptable animal survived on the ry called Wallace’s line found between Asia and relevance exists between Australia and Africa.64

Questions 9-13

...............................................................................SummaryComplete the following summary of the paragraphs of Reading Passage, using no more

than words from the Reading Passage for each answer. Write your answers in boxes 9-13

on your answer r found that continental drift instead of “land bridge” theory could explain

strange species’ distribution phenomenon. In his theory, vegetation and wildlife

9to 10mobile 11 intercontinentally. However, Eduard Suess compared the wrinkle of crust

of an old apple. Now it is well known that we are living on a constant

instead of what Suess described. Hot spot in biogeography are

”and “13”switched to concerns between two terms: “ 1265