公共英语PETS考试精选80篇背诵范文含翻译(六十二)
来源:优易学  2011-5-6 18:59:02   【优易学:中国教育考试门户网】   资料下载   外语书店

Mimicry in Plants
  Plant adaptations can be remarkably complex. Certain species of orchids, for instance, imitate female bees, other plants look and smell like dead animals, and still others have the appearance of stones. These strange adaptations to life represent just a few of the sophisticated means by which plants enhance their chances of survival. Mimicry in plants or animals is a three part system. 
  There is a model: the animal, plant or substrate being initiated. There is a mimic: the organism that imitates the model. And there is a signal receiver or dupe: the animal that cannot effectively distinguish between the model and the mimic. Mimetic traits may include morphological structures, color patterns, behaviors or other attributes of the mimic that promote its resemblance to a model. 
  That model may be either an unrelated species or an inanimate object, such as the background against which an organism spends most of its time. 
  Mimicry is not an active strategy on the part of an individual plant; flowers do not deliberately trick or deceive animals into visiting them. 
  Mimicry arises as the result of evolution through natural selection and the occurrence of random  genetic mutations that lead over many generations to the appearance of favorable characteristics. If such traits help to camouflage a plant, for example, the plant is likely to have a survival  advantage  over other plants that are less well camouflaged. 
  The plant will  leave more descendants, thereby passing the advantage to the next generation. For natural selection to favor the evolution of mimicry, the mimicry must derive a reproductive advantage from modeling itself after another organism or object: its fitness, measured as the number of offspring produced that survive into the next generation, must be increased as the result of deception.

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