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Chapter 7

Chapter 7. Biological Diversity. Biological Diversity and Biological Evolution. Biological Diversity The variety of life-forms commonly expressed as the number of species in an area Biological Evolution The change in inherited characteristics of a population from generation to generation

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Chapter 7

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  1. Chapter 7 Biological Diversity Botkin and Keller Environmental Science 5e

  2. Biological Diversity and Biological Evolution • Biological Diversity • The variety of life-forms commonly expressed as the number of species in an area • Biological Evolution • The change in inherited characteristics of a population from generation to generation • One of the features that distinguishes life from everything else in the universe Botkin and Keller Environmental Science 5e

  3. Four Processes that Lead to Evolution • Mutation • Natural Selection • Migration • Genetic Shift Botkin and Keller Environmental Science 5e

  4. Mutation • A chemical change in a DNA molecule • Affects the expressed characteristics when cells or individual organisms reproduce Botkin and Keller Environmental Science 5e

  5. Natural Selection • 4 Characteristics: • Genetic Variability • Environmental Variability • Differential Reproduction • Environmental Influence • Species: • a group of individuals that reproduce with each other Botkin and Keller Environmental Science 5e

  6. Migration • Two new species evolve from an original species due to isolation • Ex: land bridge Botkin and Keller Environmental Science 5e

  7. Genetic Drift • Changes in the frequency of a gene in a population due to chance • Can be a problem for rare or endangered species Botkin and Keller Environmental Science 5e

  8. Basic Concepts of Biological Diversity • Genetic Diversity • Habitat Diversity • Species Diversity • Species Richness • Species Evenness • Species Dominance Botkin and Keller Environmental Science 5e

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  12. The Number of Species of Life on Earth • No one knows the exact number • About 1.4 million species have been identified and named • Insects and plants make up moth of these species • Number will increase Botkin and Keller Environmental Science 5e

  13. The Competitive Exclusion Principles • 2 species that have exactly the same requirements cannot coexist in exactly the same habitat • Ex) introduction of the gray squirrel into Great Britain Botkin and Keller Environmental Science 5e

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  15. Professions and Places: The Ecological Niche and the Habitat • Habitat: where a species lives • Ecological Niche: a species profession • The reason more species do not die out from competition is that they have developed a niche, and thus avoid competition Botkin and Keller Environmental Science 5e

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  17. Species Engage in 3 Basic Interactions • 1. Competition • 2. Symbiosis • 3. Predation-Parasitism • Each affect evolution, persistence of a species and the overall diversity of life • Organisms have evolved together and therefore adjusted to one another • Human interventions upset these adjustments Botkin and Keller Environmental Science 5e

  18. Symbiosis • The relationship between 2 organisms that is beneficial to both and enhances each organisms chances of persisting • Obligate symbionts: • a symbiotic relationship between two organisms in which neither by themselves can exist without the other • Ex) stomach of a reindeer Botkin and Keller Environmental Science 5e

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