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8th Grade Science Lecture 6 Environmental Impact Over Time Ozgur Unal 8th Grade Science Lesson Objectives: 1)Explain how living and nonliving environmental factors impact evolution. 2)Describe how natural selection occurs in a species. 3)Compare and contrast selective breeding and natural selection. Survival and the Environment Would you be more likely to see a polar bear or a monkey where you live? Living and non-living factors influence the survival of a species. Species and the Environment How come so many species came to exist on Earth? Charles Darwin and Alfred R Wallace separately concluded that different, long term, environmental influences on populations produced the variety of species. What does this mean? Natural Selection According to Darwin and Wallace, changes happen from generation to generation. These changes result in adaptation to environment evolution Evolution is the change in the genetics of a species over time. How does evolution take place in nature? Darwin’s theory of evolution explains this by natural selection. Natural Selection Darwin and Wallace proposed that organisms that are better adapted to an environment survive and reproduce at a greater rate than organisms that are not. This is called natural selection. Check out Figure 14!! Mutation A change in genotype might change the phenotype. Mutation is the process in which DNA changes result in new alleles. Not all mutations are good for survival! Selective Breeding Certain types of animals and plants are carefully bred by humans for benefits. Direction of Evolution Revisit Figure 14!! The production of several species from one ancestral species is called adaptive radiation. Extinction of Species Do dinosaurs exist today? Extinction occurs when the last individual of a species die. Not only dinosaurs, millions of species became extinct throughout the history of Earth. What are the reasons for extinction? Check out Figure 16!!