Chapter 5

Essential Environment: The Science behind the Stories (3rd Edition)

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5 Evolution, Biodiversity, and Population Ecology Chapter Objectives This chapter will help students: Explain the process of natural selection and cite evidence for this process Describe the ways in which evolution influences biodiversity Discuss reasons for species extinction and mass extinction events List the levels of ecological organization Outline the characteristics of populations that help predict population growth Assess logistic growth, carrying capacity, limiting factors, and other fundamental concepts in population ecology Identify efforts and challenges involved in the conservation of biodiversity Lecture Outline 9. Central Case: Striking Gold in a Costa Rican Cloud Forest 1. Local residents in Costa Rica’s mountainous Monteverde region told of an elusive golden toad that appeared only in the early rainy reason. 2. In 1964, Dr. Jay M. Savage and his colleagues encountered hundreds of golden toads during an expedition. 3. The newly discovered species went extinct 25 years later when global climate change caused drying of the forest. 35. Evolution as the Wellspring of Earth’s Biodiversity A. Natural selection shapes organisms and diversity. 1. Biological evolution consists of genetic change in
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organisms across generations.
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2. Natural selection is the process by which traits that enhance survival and reproduction are passed on more frequently to future generations, altering the genetic makeup of populations through time. 3. In 1858, Charles Darwin and Alfred Russell Wallace each independently proposed the concept of natural selection as a mechanism for evolution and as a way to explain the great variety of living things. 1. Individuals of the same species vary in their characteristics. 2. Organisms produce more offspring than can possibly survive. 3. Some offspring may be more likely than others to survive and reproduce. 4. Characteristics that give certain individuals an advantage in surviving and reproducing might be inherited by their offspring. 5. These characteristics would tend to become more prevalent in the population in future generations. 4.
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Chapter 5 - 5 Evolution Biodiversity and Population Ecology...

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