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“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 Frankfurt1，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 Guelph2 in Ontario3，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．Onee 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) 4．

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．

詞匯:

cryptic/5kriptik/adj．隱蔽的；隱藏的 taxon/5tAksCn/ n．(生物的) 分類單元

biodiversity n．生物多樣性 taxonomic adj．分類 (學)

DNA n．脫氧核糖核酸 non-interbreeding adj．非雜交繁殖的

(deoxyribonucleic acid 的縮寫)morphology/mC:5fClEdVi/n．形態(tài)學 malaria/mE5lZEriE/ n．瘧疾

reptile/5reptail/n．爬行動物 sibling/5sibliN/n．同胞，同屬

temperate/5tempErit/adj．(氣候) 溫帶的

注釋：

1． the Goethe-Universitat in Frankfurt：德國法蘭克福大學，即Johann Wolfgang Goethe- Universitat Frankfurt am Main，位于美因和萊茵兩河匯流處的法蘭克福。

2． the University of Guelph：圭爾夫大學。該校成立于1964年，是一所公立的綜合性大學。在2005年加拿大綜合類大學評比中，圭爾夫大學名列第3名，是全加拿大最著名的高等學府之一。

3． Ontario：安大略。加拿大中東部的一個省。

4． the World Conservation Union：世界自然保護聯(lián)盟。全球最大、最重要的自然保護網(wǎng)絡(luò)機構(gòu)，它集合了82個國家、111個政府機構(gòu)、800多個非政府組織以及來自181個國家的約1萬多名科學家和專家，形成了世界環(huán)保領(lǐng)域里獨一無二的全球性合作關(guān)系。

練習：

1． 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 researchareas．

B The restllts of the research can help the development of biodiversityestimates．

C The results of the research can help our understanding of infectious diseaseevolution．

D The results of the research can help our understanding of “survival of thefittest．”

2． What was scientists’ understanding of cryptic species?

A They occurred in equal numbers in all biogeographical regions．

B They were mostly found in insects find reptiles．

C They were likely to be in tropical rather than temperate regions．

D Both B and C．

3． Do scientists know how many cryptic species exist?

A Not yet．

B Yes，they do．

C They will know the answer in another one or two years;

D They will never know the answer．

4． 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．

5． People were confused in their attempts to control malaria in Europe in the early1900s，because scientists

A identified only one mosquito species instead of six species．

B thought only three mosquito species transmitted disease．

C thought there was only one mosquito species．

D did not know what species was being studied．

答案與題解：

1． D 短文的第一段第二句的大意是，研究結(jié)果為廣泛的研究領(lǐng)域提供啟示，包括生物多樣性研究，還能幫助我們理解傳染疾病及其演變。所以，選項A、B、C都是正確的，它們不是答案。選項D的“適者生存”的內(nèi)容文章中沒有提及，因此是本題的答案。

2． D 短文的第二段第二句描述的是科學家目前的研究結(jié)果，第三段描述的是科學家在這之前對于cryptic species的理解。本題用的是過去式，問的是過去的狀況，因此，答案在第三段中，B和C是答案，所以D是正確選擇。

3． A 第三段和第五段提供了答案。第三段的倒數(shù)第二句中的Until．．．no one will know just how many cryptic species exist．其意思就是人們目前還不了解。第五段的最后一句也說明了研究者目前對此尚未了解。

4． C 答案在第六段中。該段舉了非洲大象為例，說明什么是cryptic species。第六段的句子“A 2001 study found the elephants were actually two genetically distinct，non- interbreeding spemes”是選擇C的依據(jù)。選項A不對，the WCU并沒有雜交繁殖這兩種象。選項B不對，短文說這兩種象是非雜交物種。選項D的內(nèi)容短文中找不到。

5． A 短文最后一段告訴我們，由于對蚊子種類不了解，20世紀初期瘧疾曾肆虐歐洲，最終，科學家才了解到蚊子這一物種不是由一個種類而是由六個種類組成。所以，應(yīng)該選擇A。