BIOLOGY FOR LIFE
  • IB Bio Syllabus
    • Unity and Diversity (A) >
      • A1 molecules >
        • A1.1: Water
        • A1.2: Nucleic Acids
      • A2 Cells >
        • A2.1: Origins of Cells
        • A2.2: Cell Structure
        • A2.3: Viruses
      • A3 Organisms >
        • A3.1: Diversity of Organisms
        • A3.2: Classification and Cladistics
      • A4 Ecosystems >
        • A4.1: Evolution and Speciation
        • A4.2: Conservation of Biodiversity
    • Form and Function (B) >
      • B1 Molecules >
        • B1.1: Carbohydrates and Lipids
        • B1.2: Proteins
      • B2 Cells >
        • B2.1 Membranes and Membrane Transport
        • B2.2 Organelles and Compartmentalization
        • B2.3 Cell Specialization
      • B3 Organisms >
        • B3.1 Gas Exchange
        • B3.2 Transport
        • B3.3 Muscle and Motility
      • B4 Ecosystems >
        • B4.1 Adaptation to Environment
        • B4.2 Ecological Niches
    • Interaction and Interdependence (C) >
      • C1 Molecules >
        • C1.1: Enzymes and Metabolism
        • C1.2: Cell Respiration
        • C1.3: Photosynthesis
      • C2 Cells >
        • C2.1: Chemical Signaling
        • C2.2: Neural Signaling
      • C3 Organisms >
        • C3.1: Integration of Body Systems
        • C3.2: Defense Against Disease
      • C4 Ecosystems >
        • C4.1 Populations and Communities
        • C4.2 Transfers of Energy and Matter
    • Continuity and Change (D) >
      • D1 Molecules >
        • D1.1: DNA Replication
        • D1.2: Protein Synthesis
        • D1.3: Mutation and Gene Editing
      • D2 Cells >
        • D2.1: Cell and Nuclear Division
        • D2.2: Gene Expression
        • D2.3: Water Potential
      • D3 Organisms >
        • D3.1: Reproduction
        • D3.2: Inheritance
        • D3.3: Homeostasis
      • D4 Ecosystems >
        • D4.1: Natural Selection
        • D4.2: Stability and Change
        • D4.3: Climate Change
  • IB Requirements
    • Internal Assessment >
      • Research Design
      • Analysis
      • Conclusion
      • Evaluation
    • External Assessment >
      • Exam Revision
    • Extended Essay
    • Reflective Project
    • Collaborative Sciences Project
    • Learner Profile
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        • Addressing Safety
        • Measuring Variables >
          • Lab Drawings
          • Measurement Uncertainty
        • Techniques >
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      • Technology >
        • Graphing with Excel
      • Mathematics >
        • Statistics >
          • Glossary of Statistic Terms and Equations
          • Descriptive Statistics >
            • Skew and the Normal Distribution
            • Outliers
            • Measures of Central Tendancy
            • Measures of Spread
            • Pearson Correlation
          • Inferential Statistics >
            • T-Test
            • ANOVA
            • Kruskal-Wallis
            • X2 Test for Independence
            • X2 Goodness of Fit
        • Graphing >
          • Interpreting Error Bars
    • Inquiry Processes >
      • Exploring & Designing >
        • Research Questions
        • Hypotheses and Predictions
        • Varaibles
        • Sampling
      • Collecting & Processing Data >
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        • Error Analysis
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D4.1  Natural Selection

Guiding Questions:  
Guiding questions help students view the content of the syllabus through the conceptual lenses of both the themes and the levels of biological organization.
​
  • What processes can cause changes in allele frequencies within a population?
  • What is the role of reproduction in the process of natural selection?
​​
​Linking Questions:  
Linking questions strengthen students’ understanding by making connections between topics.  The ideal outcome of the linking questions is networked knowledge.
  • How do intraspecific interactions differ from interspecific interactions? 
  • What mechanisms minimize competition?
D4.1.1— Natural selection as the mechanism driving evolutionary change.
  • Define natural selection.
  • Outline the observations and inferences that lead to the development of the theory of evolution by natural selection. 
  • Outline the theory of evolution by natural selection as an example of inductive reasoning.
  • Outline the theory of evolution by natural selection as an example of the correspondence, coherence and pragmatic theories of truth.
  • State that natural selection has operated continuously over billions of years, resulting in the biodiversity of life.​
D4.1.2— Roles of mutation and sexual reproduction in generating the variation on which natural selection acts.
  • Explain why natural selection can only function if there is variation in a species.
  • Outline sources of genetic variation (mutation, meiosis and sexual reproduction). 
  • Compare variation that results from mutation to that generated from sexual reproduction.
D4.1.3-- Overproduction of offspring and competition for resources as factors that promote natural selection.
  • State that species have the ability to produce more offspring than the environment can support.
  • Use an example to illustrate the potential for overproduction of offspring in a population.
  • State two evolutionary benefits of overproduction of offspring.
  • Describe competition for resources as a consequence of overproduction of offspring.
  • Define carrying capacity
  • List examples of resources that may limit population size.
  • Compare direct and indirect competition.
D4.1.4--  Abiotic factors as selection pressures.
  • Define selective pressure and density-independent.
  • State example biotic and abiotic selective pressures.
  • Outline how a selective pressure acts on the variation in a population.​
D4.1.5— Differences between individuals in adaptation, survival and reproduction as the basis for natural selection.  
  • Define adaptation and fitness.
  • Explain the effect of the selective pressure on the more and less adapted individuals in a population.
  • Explain adaptation as a consequence of natural selection. ​
D4.1.6- Requirement that traits are heritable for evolutionary change to occur.
  • Distinguish between heritable and acquired characteristics. 
  • Explain why only heritable characteristics can be acted upon by natural selection.
 ​​​​D4.1.7- Sexual selection as a selection pressure in animal species.
  • Outline the two major mechanisms of sexual selection in evolution of courtship behavior and anatomical features. 
  • Describe examples of sexual selection, including for color, size, and courtship behaviors.
D4.1.8- Modelling of sexual and natural selection based on experimental control of selection pressures.  
  • Outline the selective pressures for and against coloration in guppies.
  • Summarize John Endler’s experiments with guppies which demonstrate selection for and against coloration in different habitats.
  • Explain what models are and their purposes in science.
AHL ​​​​​​​D4.1.9- Concept of the gene pool.
  • Define gene pool, gene, allele and gene flow.
  • Describe how it is possible for multiple gene pools to exist in a single species.
AHL ​​​​​​​D4.1.10- Allele frequencies of geographically isolated populations.
  • Define allele frequency.
  • Calculate allele frequency from gene pool data. 
  • Outline reasons when allele frequencies may be different in geographically isolated populations of the same species.
  • Use a database to search for allele frequency of a human gene.​
AHL ​​​​​​​D4.1.11- Changes in allele frequency in the gene pool as a consequence of natural selection between individuals according to differences in their heritable traits.
  • Outline “neo-Darwinism” as the integration of genetic inheritance and the mechanism of natural selection.
  • State that change in the allele frequencies of a gene is evidence of evolution.
  • List processes that can change allele frequency in a population.
  • Explain how natural selection can lead to change in allele frequency in a gene pool. ​
AHL ​​​​​​​D4.1.12- Differences between directional, disruptive and stabilizing selection.
  • Outline the change in allele frequencies associated with stabilizing, disruptive and directional selection.
  • Use graphs to illustrate or identify stabilizing, disruptive and directional selection.
  • Outline an example of stabilizing, disruptive and directional selection.​
AHL ​​​​​​D4.1.13- Hardy–Weinberg equation and calculations of allele or genotype frequencies.
  • State the Hardy-Weinberg equations.
  • Given data, calculate allele frequencies of a gene in a gene pool.
  • Given data, calculate genotype frequencies of a gene in a gene pool.​
AHL ​​​​​​D4.1.14- Hardy–Weinberg conditions that must be maintained for a population to be in genetic equilibrium.
  • List the conditions under which populations maintain Hardy-Weinberg equilibrium.
  • Explain how comparison of allele frequencies between two isolated populations of the same species can serve as evidence that divergence is (or is not) occurring.
  • Explain how comparison of allele frequencies between one population at two points in time can serve as evidence that evolution is (or is not) occurring.​
AHL ​​​​​​D4.1.15- Artificial selection by deliberate choice of traits. 
  • Define artificial selection.
  • Outline the mechanism of artificial selection in evolution of crop plants and domestic animals.
  • Describe an example of artificial selection of a crop plant or domestic animal.​
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Picture
  • IB Bio Syllabus
    • Unity and Diversity (A) >
      • A1 molecules >
        • A1.1: Water
        • A1.2: Nucleic Acids
      • A2 Cells >
        • A2.1: Origins of Cells
        • A2.2: Cell Structure
        • A2.3: Viruses
      • A3 Organisms >
        • A3.1: Diversity of Organisms
        • A3.2: Classification and Cladistics
      • A4 Ecosystems >
        • A4.1: Evolution and Speciation
        • A4.2: Conservation of Biodiversity
    • Form and Function (B) >
      • B1 Molecules >
        • B1.1: Carbohydrates and Lipids
        • B1.2: Proteins
      • B2 Cells >
        • B2.1 Membranes and Membrane Transport
        • B2.2 Organelles and Compartmentalization
        • B2.3 Cell Specialization
      • B3 Organisms >
        • B3.1 Gas Exchange
        • B3.2 Transport
        • B3.3 Muscle and Motility
      • B4 Ecosystems >
        • B4.1 Adaptation to Environment
        • B4.2 Ecological Niches
    • Interaction and Interdependence (C) >
      • C1 Molecules >
        • C1.1: Enzymes and Metabolism
        • C1.2: Cell Respiration
        • C1.3: Photosynthesis
      • C2 Cells >
        • C2.1: Chemical Signaling
        • C2.2: Neural Signaling
      • C3 Organisms >
        • C3.1: Integration of Body Systems
        • C3.2: Defense Against Disease
      • C4 Ecosystems >
        • C4.1 Populations and Communities
        • C4.2 Transfers of Energy and Matter
    • Continuity and Change (D) >
      • D1 Molecules >
        • D1.1: DNA Replication
        • D1.2: Protein Synthesis
        • D1.3: Mutation and Gene Editing
      • D2 Cells >
        • D2.1: Cell and Nuclear Division
        • D2.2: Gene Expression
        • D2.3: Water Potential
      • D3 Organisms >
        • D3.1: Reproduction
        • D3.2: Inheritance
        • D3.3: Homeostasis
      • D4 Ecosystems >
        • D4.1: Natural Selection
        • D4.2: Stability and Change
        • D4.3: Climate Change
  • IB Requirements
    • Internal Assessment >
      • Research Design
      • Analysis
      • Conclusion
      • Evaluation
    • External Assessment >
      • Exam Revision
    • Extended Essay
    • Reflective Project
    • Collaborative Sciences Project
    • Learner Profile
  • Skills for Biology
    • Tools >
      • Experimental Techniques >
        • Addressing Safety
        • Measuring Variables >
          • Lab Drawings
          • Measurement Uncertainty
        • Techniques >
          • Microscopy
      • Technology >
        • Graphing with Excel
      • Mathematics >
        • Statistics >
          • Glossary of Statistic Terms and Equations
          • Descriptive Statistics >
            • Skew and the Normal Distribution
            • Outliers
            • Measures of Central Tendancy
            • Measures of Spread
            • Pearson Correlation
          • Inferential Statistics >
            • T-Test
            • ANOVA
            • Kruskal-Wallis
            • X2 Test for Independence
            • X2 Goodness of Fit
        • Graphing >
          • Interpreting Error Bars
    • Inquiry Processes >
      • Exploring & Designing >
        • Research Questions
        • Hypotheses and Predictions
        • Varaibles
        • Sampling
      • Collecting & Processing Data >
        • Data Tables
      • Concluding & Evaluating >
        • Error Analysis
  • SHS Course Info
    • Above & Beyond >
      • Biology Club
      • Pumpkin Carving
      • Scavenger Hunt
      • Science News
      • Wood Duck Project (legacy)
      • Invasive Crayfish Project (legacy)
    • Assessment >
      • Class Grading IB Bio I
      • Class Grading IB Bio II
      • Daily Quizzes (legacy)
      • Lab Practicals (legacy)
    • Class Photos
    • Recommendations
  • Contact
    • About >
      • Philosophy
      • Resume
      • Reflection
      • Favorite Quotes
      • AEF Blog
  • Expeditions
    • Bahamas (2009)
    • Trinidad (2010)
    • Trinidad (2011)
    • Ecuador (2012)
    • Trinidad (2013)
    • Peru (2014)
    • Bahamas (2015)
    • Peru (2016)
    • Costa Rica (2017)
    • Costa Rica (2018)
    • Arizona (2022)
    • Florida (2023)
    • Belize (2024)
    • Costa Rica (2025)
  • Summer Ecology Research
  • Teacher Resources