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1、A Simulation of the Process of EvolutionModified from Biology Labs On-Line (Pearson)Biology Labs On-line “EvolutionLab” is a simulation which allows you to study the principles and processes behind the concept of evolution by natural selection. It employs two hypothetical islands, which harbor popul
2、ations of finches. Here, you will examine biological and environmental factors that influence the long term changes in these populations.The purpose of this exercise is to: Simulate changes that in nature would require considerable time so that basic principles can be illustrated. Help you develop a
3、n understanding of important factors that affect the evolution of a species. Demonstrate important biological and environmental selection factors that influence evolution by natural selection Help you recognize the relationship among environmental factors, variation in phenotype, and variation in in
4、dividual fitness and how this affects reproductive success.Background InformationEvolution is the study of how modern organisms have descended from the earliest life-forms. The process is dependent upon the selection of individuals within a population from generation to generation that display disti
5、nct genetic, structural, and functional modifications. The ability of a population of organisms to respond to change in their environment and survive and reproduce by developing the characteristics or modifications necessary for survival is known as adaptation. Understanding how life evolves and the
6、 incredible diversity or organisms that now exist is a central concern in biology. The English naturalist Charles Darwin is generally recognized as the father of evolution. Many of Darwins now-famous hypotheses were developed as a result of his 1831 voyage on HMS Beagle, a ship commissioned by the B
7、ritish government. In this historic voyage, the Beagle traveled to many coastal areas of South America. The location that resulted in Darwins most important observations was the Galapagos Islands in the South Pacific Ocean, off the northwestern coast of South America. Darwin studied populations of G
8、alapagos tortoises and observed their feeding habits regarding the fruit of prickly pear cactuses. He also observed that many of the different islands of the Galapagos contained distinctly different varieties of finches. The finches also seemed to show certain variations in concert with their primar
9、y food source.Several years after Darwins initial voyage to the Galpagos Islands, he developed several hypotheses that he felt explained how diverse species of tortoises and finches may have developed on the different islands. He realized that although the populations of these organisms could grow r
10、apidly, tortoise and finch populations did not increase in an uncontrolled manner; rather, the populations of these animals were somehow maintained in a relatively constant size. Darwin noted that certain individual organisms in a population showed subtle structural and functional differences. Becau
11、se the habitat on each island appeared to stay the same without dramatic changes in environmental conditions such as food supply, he reasoned that there would be competition among individuals for these resources. In response to this competition, Darwin suggested, some individuals in a population wer
12、e likely to develop certain structural and functional characteristics, or traits, as a way to increase their odds of survival. Developing the traits that allow individuals to survive and reproduce in an environment is called adaptation. Assuming that certain structural differences were essential for
13、 survival, he reasoned that these organisms would be superior at surviving in an environment where individuals in a population were competing for limited resources. Such favorable structural differences would be maintained or inherited over many generations, while less favorable structural differenc
14、es were likely to be lost. This line of thinking is often referred to as “survival of the fittest” because, over time, a population would consist of organisms that inherited those favorable traits that are best suited for survival of the population.Darwin proposed that evolution of a population in t
15、his fashion occurred by natural selection, because the environment selects for individuals with traits that allow them to adapt to a given environment. Because of the greater fitness of these organisms, they would be more likely to produce the greatest number of offspring, whereas those organisms th
16、at possessed less favorable abilities would be more likely to die. The term fitness is used to describe the reproductive success of an organism. Environmental factors that influence adaptation can be nonliving (abiotic) environmental components or living (biotic) components, such as competition of organisms for a food source or mating behaviors of a population. Over many generations, natural selection results in changes in the individ
