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General Ecology_Ecology
Chapter 3: Evolution - History, Evidence, and Mechanisms

Chapter 3: Evolution - History, Evidence, and Mechanisms

Last updated

Aug 24, 2022
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- 2.8: Past Climate Change
- 3.1: Understanding Evolution

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Learning Objectives

Explain evolution as an underlying theme in biology
Describe adaptations as a general concept
Describe the wide range of adaptations of individual species use to interact with and adjust to variations in their environment 
Discuss misconceptions about the theory of evolution
Identify the major requirements of natural selection
Explain the relationships among adaptation, natural selection, and evolution
Compare and contrast additional mechanisms of evolution: mutation, genetic drift, and gene flow.

3.1: Understanding Evolution
Evolution, the unifying theory of biology, describes the change and diversification of species over time. All species of living organisms, including bacteria and chimpanzees, evolved at some point from a different species. Although it may seem that living things today stay the same, this is not the case: evolution is a gradual and ongoing process.
3.2: Evidence of Evolution
Evidence of evolution includes fossils, embryology, vestigial structures, homology, modern case studies, and human-influenced evolution ('artificial' selection).
- 3.2.1: Scientist Spotlight - Ynes Enriquetta Julietta Mexia
3.3: Natural Selection and Adaptive Evolution
Natural selection drives adaptive evolution by selecting for and increasing the occurrence of beneficial traits in a population. Natural selection only acts on the population’s heritable traits: selecting for beneficial alleles and, thus, increasing their frequency in the population, while selecting against deleterious alleles and, thereby, decreasing their frequency. This process is known as adaptive evolution.
3.4: Additional Mechanisms of Evolution
In addition to natural selection, the evolution of populations is also influenced by mutation, genetic recombination, genetic drift, and gene flow.

Cover photo: "Dinosaur footprint" (Greg Willis, CC BY-SA 2.0)

Learning Objectives

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