"Hidden" Species May Be Surprisingly Common
Cryptic species animals that appear identical but are genetically quite distant—may be much more widespread than previously thought. The findings could have major implications in areas ranging from biodiversity estimates and wildlife management, to our understanding of infectious diseases and evolution.
Reports of cryptic species have increased dramatically over the past two decades with the advent of relatively inexpensive DNA sequencing technology. Markus Pfenninger and Klaus Schwenk, of the Goethe-Universitat, in Frankfurt, Germany, analyzed all known data on cryptic animal species and discovered that they are found in equal proportions throughout all major branches of the animal kingdom and occur in equal numbers in all biogeographieal regions.
Scientists had previously speculated that cryptic species were predominantly found in insects and reptiles, and were more likely to occur in tropical rather than temperate regions. "Species that are seemingly widespread and abundant could in reality be many different cryptic species that have low populations and are highly endangered. " Says Pfenninger. Until the genetic information of all species in at least one taxon is thoroughly studied, no one will know just how many cryptic species exist. "It could be as high as 30%. " Pfenninger says.
"I'm extremely surprised by their results. " Says Alex Smith of the University of Guelph in Ontario, Canada. "It's a call to arms to keep doing the broad kind of genetic studies that we are doing. "
Sampling as many individuals as possible, scientists hope to complete work on all fish and birds in another 5 to 10 years. Once either of these taxonomic groups is completed, Pfenninger says researchers will be able to decide how many cryptic species exist throughout the animal kingdom.
Examples of cryptic species include the African elephant. A 2001 study found the elephants were actually two genetically distinct, non-interbreeding species, the African bush elephant and the African elephant. The species are currently listed as vulnerable and threatened, respectively, by the World Conservation Union (WCU).
The reclassifications are more than an academic exercise. They define populations that have evolved independently of each other and whose genetic differences can have significant consequences. In the early 1900s misidentification of mosquito species based on morphology confused attempts to control malaria in Europe. Ultimately, what was thought to be a single species was actually made up of six sibling species, only three of which transmitted the disease. "The basic unit in biology is always the species, and you have to know what you are dealing with. " Pfenninger says. Much previous research is now no longer used, he says, because it is not clear what species was being studied.
Which of the following about the significance of the research on cryptic species is NOT true?
A．The results of the research can help the development of many other research areas.
B．The results of the research can help the development of biodiversity estimates.
C．The results of the research can help our understanding of infectious disease evolution.
D．The results of the research can help our understanding of "survival of the fittest. "
第1题：
E
A rainforest is an area covered by tall trees with the total high rainfall spreading quite equally through the year and the temperature rarely dipping below l6℃．Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate．Without the forest cover，these areas would reflect more heat into the atmosphere，warming the rest of the world. Losing the rainforests may also influence wind and rainfall patterns，potentially causing certain natural disasters all over the world．
In the past hundred years，humans have begun destroying rainforests in search of three major resources(资源)：land for crops，wood for paper and other products，land for raising farm animals．This action affects the environment as a whole．For example，a lot of carbon dioxide (二氧化碳)in the air comes from burning the rainforests．People obviously have a need for the resources we gain from cutting trees but we will suffer much more than we will benefit.
There are two main reasons for this．Firstly，when people cut down trees，generally they can only use the land for a year or two．Secondly，cutting large sections of rainforests may provide a good supply of wood right now，but in the long run it actually reduces the world’s wood supply．
Rainforests are often called the world’s drug store．More than 25％ of the medicines we use today come from plants in rainforests．However，fewer than l％of rainforest plants have been examined for their medical value．It is extremely likely that our best chance to cure diseases lies somewhere in the world’s shrinking rainforests．
72．Rainforests can help to adjust the climate because they ．
A．reflect more heat into the atmosphere
B．bring about high rainfall throughout the world
C．rarely cause the temperature to drop lower than l6℃
D．reduce the effect of heat from the sun on the earth
第2题：
If cloned animals could be used as organ donors, ().
A、people don’t have to worry about cloning twins for transplants
B、raising animals such as pigs can help solve the problem
C、the human body attacks and destroys tissue from other species
D、it may be more efficient to produce such animals by cloning than by cur
第3题：
Which of the following about the African bush elephant and the African elephant is true?
A．The WCU are interbreeding those elephants.
B．They are interbreeding species.
C．They are two genetically distant species.
D．They depend on each other for survival.
第4题：
第5题：
A、hunted
B、hunting
C、that hunted
D、are hunted
第6题：
Prehistoric men and women enjoyed a more varied diet(饮食)than people do now, since they ate species(种类)of plant and several hundred thousand types of living things. But only a tiny percentage of these were ever domesticated(驯化). Modern shops have hastened a trend towards specialization which began in the earliest days of agriculture. The food of rich countries has become cheaper relative to wages. It is speedily distributed in supermarkets, but the choice annually becomes less and less great. Even individual foods themselves become more standardized. We live in the world of the carrot specially blunted in order to avoid making a hole in the bag, and the tomato grown to meet a demand for a standard weight of eighteen tomatoes to a kilo. Siri von Reis Altschul asks: "Only the tree major cereals(谷物)and perhaps ten other widely cultivated species stand between famine and survival for the world's human population and a handful of drug plants has served Western civilization for several thousand years. A rather obvious question arises: are we missing something?" After all, there are 800,000 species of plant on earth.
1. In prehistoric times people _____.
A. ate much more than we do today
B. lived mainly on plant food
C. had a wide-ranging diet
D. were more fussy about what they ate
2. Most of us have come to expect _____.
A. no variation in our diet
B. a reduction in food supplies
C. a specialist diet
D. food conforming to a set standard
3. The specialization of food was started by _____.
A. the emergence of supermarkets
B. the rise of agriculture
C. the rich countries
D. the modern shops
4. According to the passage, people in the West today survive on _____.
A. carrots and tomatoes
B. several thousand types of plants and cereals
C. a very small number of cultivated foods
D. special species planted one thousand years age
5. The conclusion seems to be that we _____.
A. could make use of more natural species
B. don't cultivate the right kind of food
C. produce more food than we need
D. cultivate too many different species
第7题：
Prehistoric men and women enjoyed a more varied diet than people do now, since they ate species of plant and several hundreds thousands types of living things. But only a tiny percentage of these were ever domesticated. Modern shops have hastened a trend towards specialization which began in the earliest days of agriculture. The food of the rich countries has become cheaper relative to wages. It is speedily distributed in supermarkets. But the choice annually becomes less and less great. Even individual foods themselves become more standardized. We live in the world of carrot specially blunted in order to avoid making a hole in the bag, and the tomato grown to meet a demand for a standard weight of weighting tomatoes to a kilo. Siri von Reis asks: "Only the three major cereals (谷物类食物) and perhaps ten other widely cultivated species stand between famine and survival for the world's human population and a handful of drug plants has served Western civilization for several thousand years. A rather obvious question arises: Are we missing something?" After all, there are 800 000 species of plant on earth.
1、In prehistoric times people____.
A、ate much more than we do today
B、lived mainly on plant food
C、had a wide-ranging diet
D、were more fussy about what they ate
2、Most of us have come to expect____.
A、no variation in our diet
B、a reduction in food supplies
C、a specialist diet
D、food conforming to a set standard
3、The specialization of food was started by____.
A、the emergence of supermarkets
B、the rise of agriculture
C、the rich countries
D、the modern shops
4、According to the passage, people in the West today survive on____.
A、carrots and tomatoes
B、several thousand types of plants and cereals
C、a very small number of cultivated foods
D、special species planted one thousand years ago
5、The conclusion seems to be that we____.
A、could make use of more natural species
B、don't cultivate the right kind of food
C、produce more food than we need
D、cultivate too many different species
第8题：
C
We have met the enemy, and he is ours. We bought him at a pet shop. When monkey-pox, a disease usually found in the African rain forest, suddenly turns up in children in the American Midwest, it’s hard not to wonder if the disease that comes from foreign animals is homing in on human beings. “Most of the infections (感染) we think of as human infections started in other animals,” says Stephen Morse, director of the Center for Public Health Preparedness at Columbia University.
It’s not just that we’re going to where the animals are; we’re also bringing them closer to us. Popular foreign pets have brought a whole new disease to this country. A strange illness killed Isaksen’s pets, and she now thinks that keeping foreign pets is a bad idea. “I don’t think it’s fair to have them as pets when we have such a limited knowledge of them,” says Isaksen.
“Laws allowing these animals to be brought in from deep forest areas without stricter control need changing,” says Peter Schantz. Monkey-pox may be the wake-up call. Researchers believe infected animals may infect their owners. We know very little about these new diseases. A new bug (病毒) may be kind at first. But it may develop into something harmful (有害的). Monkey-pox doesn’t look a major infectious disease. But it is not impossible to pass the disease from person to person.
64. We learn from Paragraph 1 that the pet sold at the shop may _________.
A. come from ColumbiaB. prevent us from being infected
C. enjoy being with children D. suffer from monkey-pox
第9题：
第10题：