1740406391-Variation Selection

Variation & Natural Selection

Overview

• Topic: Variation & Selection

• Focus on how variations exist within species and impact natural selection.

Page 1: Introduction to Variation and Selection

• Lesson Name: Variation & Selection

• The content explores the concepts of variation among species and the principle of natural selection.

Page 2: Attendance & Instructions

• Attendance: Ensuring participants are present for the lesson.

• Collaborate Board: Encouraging collaboration among students.

Page 3: Video Reference

• Title: VARIATI Video

• Channels concepts of variation within genetics related to biology.

Page 4: Fill in the Blanks

• Engage students to enhance understanding through interactive activities.

Page 5: Understanding Variation

• Definition of Variation: Differences between individuals of the same species.

• Phenotypic Variation: Observed differences in features due to genetic diversity.

  • Variations are often a result of genetic differences.

Page 6: Types of Phenotypic Variation

• Continuous Variation: A scale of small differences within characteristics.

  • Examples include:

    • Height

    • Mass

    • Finger length

• Discontinuous Variation: Sharp distinctions in characteristics.

  • Examples include:

    • Blood types (A, B, AB, O)

    • Gender

    • Ability to roll the tongue

    • Binary traits with no intermediates.

Page 7: Characteristics of Discontinuous Variation

• Examples illustrating traits that are distinct and non-overlapping.

• The absence of intermediates in traits such as blood groups and gender.

Page 8: Causes of Phenotypic Variation

• Genetic Variation:

  • Traits determined entirely by genetics:

    • Blood group

    • Eye color

    • Tongue rolling capability

• Environmental Variation: Influences from the organism’s surroundings.

Page 9: Listing Variations

• Encourage students to categorize:

  • Genetic Causes: Traits purely from genes.

  • Environmental Causes: Influences solely by the environment.

  • Both: Traits affected by both genetics and environment.

Page 10: Environmental Influences

• Characteristics affected by various external factors:

  • Climate, diet, culture, and lifestyle.

• Examples:

  • Accidents causing injuries or scarring.

  • Lifestyle leading to obesity.

  • Language accent influenced by the country of origin.

  • Plants adapting to light scarcity.

Page 11: Genetic vs. Environmental Effects

• Discontinuous Variation: Originating from purely genetic sources.

• Continuous Traits: Resulting from genetic and environmental interplay.

  • Example: Children of tall parents may not grow tall if nutritionally deprived.

Page 14: Mutation

• Definition: Genetic changes leading to different phenotypes.

  • Most mutations are neutral but can occasionally confer advantages.

  • Example: A color change in a bird attracts mates, enhancing reproductive success.

  • Some mutations may cause detrimental effects (e.g., sickle cell anemia).

Page 15: Mutation Causes and Effects

• Factors Increasing Mutations:

  • Ionizing radiation (e.g., gamma rays)

  • UV radiation

  • Chemicals (e.g., tar from tobacco)

• High mutation rates can lead to cancer.

Page 16: Sources of Genetic Variation

• Sources include:

  • Mutations: Random DNA changes.

  • Meiosis: Creates new allele combinations.

  • Random mating and fertilization events in reproduction impacting genetic diversity.

Page 18: Adaptive Features

• Definition: Inherited traits aiding survival and reproduction.

• Surface characteristics can illustrate adaptive features.

  • Examples:

    • Large ears for heat loss and hearing.

    • Camouflaged fur for protection.

Page 19: Plant Adaptations

• Hydrophyte Adaptations: Features for survival in water-rich areas.

• Xerophyte Adaptations: Traits enabling survival in dry environments.

  • Key adaptations:

    • Thick waxy cuticles

    • Specialized root systems

    • Leaf structure adapted to conserve water.

Page 21: Introduction to Natural Selection

• Natural Selection Theory: Survival of the fittest through adaptive traits.

  • Natural competition and resource struggle couple with reproduction pressures.

  • The advantageous alleles are passed on more frequently, influencing future generations.

Page 22: Example of Natural Selection

• Example: Variation in shell color among snails.

  • The white-shelled snails have camouflage advantages over predators, leading to higher survival and reproductive rates.

Page 24: Impact of Light vs. Dark Moths

• A shifting balance in peppered moths where dark moths thrive due to advantageous camouflage against tree bark, leading to increased reproduction and prevalence in the population.