衛生類：閱讀理解Cryptic species animals

　　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：世界自然保護聯盟。全球最大、最重要的自然保護網絡機構，它集合了82個國家、111個政府機構、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，形成了世界環保領域里獨一無二的全球性合作關系。

　　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．”