MJ

Lecture 4 Darwin and Evolution

Introduction

  • Course Context: BIOL 1113 Organisms and their Environment; Brooker et al., Chapters 1.3 and 22.1, 22.2.

  • Acknowledgment: Respect for Mi’kmaq People's territory and recognition of treaty responsibilities.

Charles Darwin and Evolutionary Theory

  • Quotations: Charles Darwin emphasizes the beauty and complexity of life evolving from simple beginnings (1859).

  • Example: Blue dragon sea slug showcases diverse evolutionary adaptations.

Evolution Basics

  • Definition: Population - A group of the same species in a specific area with potential for interbreeding.

  • Heritable Changes: Changes over generations within populations.

Charles Darwin's Contributions

  • Life Span: 1809-1882

  • Background: English naturalist and geologist; studied descent of species from common ancestors.

  • Theory of Natural Selection:

    • Eliminates individuals less likely to survive and reproduce.

    • Traits conferring reproductive success become more common.

  • Modern Synthesis (~1950s): Integrates natural selection as core to evolution.

The Voyage of the Beagle

  • Significant Journey: Inspired Darwin’s theories about species adaptation and difference.

  • Key Locations: England, Galápagos Islands, and others influenced Darwin's perspective of species traits.

Descent with Modification

  • Theory Overview:

    • Existing species evolve from modifications of predecessors.

    • Key Concepts:

      • Variation in Traits: Heritable traits are transmitted from parent to offspring.

      • Natural Selection: Organisms better suited to their environment reproduce more successfully.

Darwin's Finches Example

  • Scenario: Birds from South America diversify on islands, adapting to various seed sizes.

Connections Among Modern Life Forms

  • Evolutionary History: Modern life is linked by evolutionary processes.

  • Character Modifications: Pre-existing structures show evolutionary adaptations for differing lifestyles.

  • Efficiency of Structures: Modifications enhance survival chances and reproduction.

Genetics and Evolution

  • DNA Functionality:

    • DNA is the genetic blueprint governing life functions and traits.

    • Passed from generation to generation, stable unless mutated.

    • Genes: Segments of DNA that encode proteins, crucial for life processes.

  • Mutations:

    • Heritable changes in genetic material.

    • Can be neutral, beneficial, or detrimental depending on environmental factors.

Importance of Reproduction and Mutations

  • Reproduction: Essential for passing on beneficial mutations.

  • Survival Impact: Detrimental mutations are less likely to be inherited; beneficial mutations promote survival in changing environments.

Evolutionary Change Types

  • Vertical Descent with Mutation:

    • Traits passed through generations with accumulated mutations.

    • New species evolve from pre-existing ancestors.

  • Fossil Record Evidence: Provides insight into evolutionary changes (e.g., evolution of whales from land mammals).

Evolution of Whales

  • Evolutionary Path: Transition from terrestrial predators to fully aquatic creatures.

  • Distinct Features: Changing anatomy includes adaptations in hearing, limb structure, and breathing.

  • Atavistic Traits: Reappearance of ancestral characteristics in species evolution (e.g., hind limbs in modern whales).

Genetic Epidemiology and Vertical Evolution

  • Application: Uses genetic information to track disease progression and evolutionary adaptations (e.g., COVID-19).

Horizontal Gene Transfer

  • Definition: Genes transferred among organisms, not reliant on parent-offspring relationships (e.g., bacteria).

  • Significance: Allows survival advantages such as antibiotic resistance, less common but significant in horizontal gene transfer in bacteria and Archaea.