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Selection, evolution and speciation
Student book links
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Specification links
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2.1.19
2.1.20
2.1.21
5.1.2 (n)–(s)
Link to GCSE/AS specification
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GCSE Variation
DNA, genes and chromosomes
Genetic crosses
Selection and speciation
Classification
AS 2.3.1 Biodiversity
2.3.2 Classification
2.3.3 Evolution
Weekly learning outcomes
Students should be able to:
 Explain with examples how environmental factors can act as stabilising or evolutionary forces of
natural selection.
 Explain how genetic drift can cause large changes in small populations.
 Explain the role of isolating mechanisms in the evolution of new species – with reference to
ecological (geographic), seasonal (temporal) and reproductive mechanisms.
 Explain the significance of the various concepts of the species – with reference to the biological
species concept and the phylogenetic (cladistic/evolutionary) species concept.
 Compare and contrast natural selection and artificial selection.
 Describe how artificial selection has been used to produce the modern dairy cow and to produce
bread wheat Triticum aestivum.
Key words
Genetic drift
Phylogenetic
Paraphyletic
Clade
Reproductive
Weekly plan 18
Suggested time allowed (includes contact and non-contact time):
5 hours
Suggested teaching order
1.
2.
3.
4.
5.
6.
7.
8.
Stabilising and directional selection
Genetic drift
Isolating mechanisms
The biological species concept
The phylogenetic species concept
Compare natural and artificial selection
Artificial selection of the dairy cow
Artificial selection of bread wheat
How Science Works
Selection pressure
Stabilising selection
Directional selection
Artificial selection
Natural selection
Monophyletic
Environmental resistance
Biological species concept Polyploidy
Cladistics
Isolating mechanisms
Cladistic approach
Evolutionary force
Seasonal/temporal
Ecological/geographic
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HSW 1 Explain the significance of the various concepts of
species.
HSW 6a & 6b Describe how artificial selection has been used
to produce the modern dairy cow and bread wheat.
The web links referred to here are some that the author has found personally helpful but are not intended to be a comprehensive list, many other
good resources exist.
© Pearson Education Ltd 2009
This document may have been altered from the original
1
Weekly plan 18
Learning styles (S = Starter activities, M = Main activities, P = Plenary activities)
ICT activities
Kinaesthetic
Activity S1
Activity M2
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Interpersonal
Activities S1–3
Activities M1–3
Activities P1–3
Auditory
Activities S1–3
Activities M1–3
Activities P1–3
Suggested starter activities
Visual
Activities S1–3
Activities M1–3
Activities P1–3
Equipment
1. As a class, play Complete the story.
2. Ask students: ‘What is a species?’
Teacher notes
Write a list of words about evolution and natural selection on
the board. Begin the story yourself – each student is allowed
to add one of the words on the board to the story, they score
a point if they use it correctly.
Mini-whiteboards
3. Brainstorm students’ ideas about selective breeding.
Suggested main activities
See Activities M1, M2 and M3 below – using a word processor
or presentation software to create a table, storyboard and
diagrams.
They write their own definition on mini-whiteboards and then
organise themselves so that students with similar definitions
stand next to each other.
Using their ideas, create a concept map on the board.
Equipment
Teacher notes
1. In pairs, students create a table to compare and contrast
natural and artificial selection.
2. In groups, students create a storyboard for a TV
programme about evolution.
Prepare the scene briefs covering: stabilising/directional
selection; genetic drift; and isolating mechanisms.
3. In pairs, students develop annotated diagrams to show how
to undertake artificial selection of the modern dairy cow and
bread wheat.
Suggested plenary activities
Equipment
Teacher notes
1. Get groups of students to draw a cartoon depicting one
mechanism in the process of evolution and speciation.
A3 paper
Mechanisms can include: isolation; genetic drift; stabilising
selection; and directional selection.
Loop game cards – questions and
unrelated answers on the same card
A student reads out their question, the student with the
correct answer responds and then reads out their question
and so on.
2. In pairs, students write a mission statement for cladistics.
3. Devise a Loop game to play as a class which helps the
students recap the process of artificial selection.
© Pearson Education Ltd 2009
This document may have been altered from the original
2
Weekly plan 18
Homework suggestions
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Write a newspaper report about an imaginary debate between Carl Linnaeus and Willi Hennig. Research the ideas that each would use to support their concept of a
species and report what they would have said.
Read the Wikipedia entry for genetic drift. Précis the entry to make it clearer and to be no longer than 300 words.
Cross-curriculum links
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PSHE – nature/nurture debate in genetic vs. environmental variation
Religious studies – nature/nurture debate in genetic vs. environmental variation
Mathematics – allele frequency calculations and calculations of percentage divergence
Geographic – speciation barriers, trends in agriculture use across the world
History – history of agriculture
Stretch and Challenge
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The links to the AS specification stated on page 1 are a good opportunity to develop Stretch and Challenge skills.
Compare and contrast cladistic and Linnean approaches to taxonomy.
Create a table to describe the differences between allopatric, sympatric, parapatric and peripatric speciation.
Potential misconceptions
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Students often suggest that extant species have evolved from other extant species, e.g. humans have evolved from chimps, rather than from a common ancestor.
Some students will have a view of evolution based on faith – try to help them distinguish between science and religion as two separate systems.
Students may still hold a view of evolution as acquired characteristics.
Distinguishing between diploid and polyploid individuals can be confusing – explain carefully to students how these individuals form.
Students may believe that evolution is following a pre-defined pathway, with an aim or objective.
Students may not understand the difference between the terms ‘theory’ and ‘scientific theory’.
Students may believe that evolution is not still happening.
Notes
© Pearson Education Ltd 2009
This document may have been altered from the original
3