Lesson 1: Introduction to Evolution
Background Information
Define means to give the precise meaning of a word, phrase or physical quantity.
Syllabus definition: Evolution is the cumulative change in the heritable characteristics of a population.
Darwinian Evolution is not simply based on natural selection but was in fact a composition of at least five different 'sub theories':
1. Evolution: that all life is and has been perpetually changing. This contrasts strongly with notions that all forms of life are constant an unchanging.
2. Common descent: that all living things share a common ancestor if the traced back far enough.
3. Gradualism: that evolutionary change takes places slowly and gradually. This contrasts with saltation in which changes are sudden and extreme.
4. Multiplication of species: the diversity of life is a consequence of speciation. Populations adapting to locations and becoming reproductively isolated from other populations.
5. Natural selection: a two stage process in which there is: 1) production of genetic variation and 2) selection
Syllabus definition: Evolution is the cumulative change in the heritable characteristics of a population.
Darwinian Evolution is not simply based on natural selection but was in fact a composition of at least five different 'sub theories':
1. Evolution: that all life is and has been perpetually changing. This contrasts strongly with notions that all forms of life are constant an unchanging.
2. Common descent: that all living things share a common ancestor if the traced back far enough.
3. Gradualism: that evolutionary change takes places slowly and gradually. This contrasts with saltation in which changes are sudden and extreme.
4. Multiplication of species: the diversity of life is a consequence of speciation. Populations adapting to locations and becoming reproductively isolated from other populations.
5. Natural selection: a two stage process in which there is: 1) production of genetic variation and 2) selection
The consequence of the potential overproduction of offspring is a struggle for survival.
- The population produces more offspring than the carrying capacity of the environment can support
- Offspring/population compete for limited resources (Intraspecific competition)
- Some individuals have characteristic (or combination ) that give them a competitive advantage.
- These individuals are consequently 'fitter' in terms of freedom from disease, food availability etc.
- These individuals are more likely to successfully reproduce (offspring survive)
- Through inheritance of the genes for these advantageous characteristics the frequency of these characteristics become greater in the next generation.
- The alleles for the advantageous characteristic becomes more frequent in the population
- It should be noted that the 'struggle for survival' in this model is a consequence of over-population.
- The struggle takes the form of individuals in the population being 'selected for' or selected against'
- Survivors form the new breeding population.
- The frequency of advantageous alleles has increased.
- The change in the heritable characteristics is by definition evolution.
Hook: The Evolution of Dance
Video: http://www.youtube.com/watch?v=dMH0bHeiRNg&noredirect=1 (~6 minutes)
Video: http://www.youtube.com/watch?v=dMH0bHeiRNg&noredirect=1 (~6 minutes)
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Explains ways in which it is a metaphor for evolution in biology:
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Diagnostic - KWL Chart
Action
Card Activity
Narrative/Practice
Additional Teaching Ideas
Which Came First? The Chicken or the Egg? -- http://www.youtube.com/watch?feature=player_embedded&v=1a8pI65emDE
Diagnostic - KWL Chart
Action
Card Activity
- Lesson Plan: http://www.indiana.edu/~ensiweb/lessons/ns.cum.l.html
- http://www.indiana.edu/~ensiweb/lessons/ns.cum.h.pdf (instructions for teachers)
Narrative/Practice
- Ensure that students have a basic understanding of traits, adaptations and mutations and can distinguish between the terms population, species, individual and generation.
- Connect to previous topics: biodiversity and classification
- Random vs Non-Random mating, Selective Advantage
- Variation/ Adaptation: Peppered Moths
- Mutation, “Survival of the fit enough”
Additional Teaching Ideas
Which Came First? The Chicken or the Egg? -- http://www.youtube.com/watch?feature=player_embedded&v=1a8pI65emDE
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Another interesting hook that introduces topics to be covered in this unit:
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The Evolution of Life -- http://youtu.be/H2_6cqa2cP4
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This can be used as both a review of the taxonomy unit and as a means of starting discussion on how exploring the mechanisms by which animals begun to diverge.
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