EvoPhy Lecture 3 – Natural Selection

Evolution & Phylogeny

  • Course: AEBI 212

  • Instructor: Dr. Morgan Jackson (he/him)

  • Schedule: Mondays and Wednesdays 11:35-12:55

  • Lecture Topic: Natural Selection

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Key Historical Figure: Alfred Russel Wallace

  • In 1858, Darwin received a letter from Wallace, who admired Darwin's work and wished to discuss his ideas.

  • Wallace was significantly influenced by Darwin and shared similar theories on natural selection.

Wallace's Background

  • Alfred Russel Wallace (1823-1913)

  • Background: Left school at age 14 and worked as a surveyor.

  • Collaboration: Joined Henry Walter Bates on expeditions, inspired by Darwin.

Wallace's Travels and Contributions

  • Conducted studies in various regions including the Sulu Sea and East Kalimantan.

  • Made significant discoveries that paralleled Darwin's theories.

Joint Publication

  • In July 1858, the Linnean Society of London saw the first acknowledgment of Darwin and Wallace's independent work on evolution.

  • Charles Lyell and Joseph Hooker presented their findings, crediting both men.

Darwin's Major Work

  • "On the Origin of Species" published on November 24, 1859.

  • Content: 502 pages detailing Darwin's thoughts and evidence for natural selection.

  • Legacy: Published six editions with updates reflecting criticism.

Revolutionary Ideas in Natural Selection

  • Key Points:

    • Natural Selection affects Populations.

    • The concept of Common Ancestry with Branching Descent.

Understanding Natural Selection

  • Requirements for Natural Selection:

    • Variation: Differences among individuals in a species.

    • Differential Reproductive Success: Variation leads to different numbers of surviving offspring based on genetic traits.

    • Inheritance: Traits that can be passed down to future generations.

Darwin's View on Natural Selection

  • Quote from Darwin: "Natural selection is daily scrutinizing every variation..." highlights the process of natural selection acting continuously in nature, shaping the evolution of species over long timeframes.

Evolutionary Experiments

  • William Dallinger (1839-1909):

    • First controlled evolution experiment (1880-1886).

    • Heat tolerance study with protozoa, demonstrating evolutionary change through environmental pressures.

Definition Clarifications

  • Natural Selection: A process where beneficial traits increase in frequency due to enhanced survival.

  • Traits: Observable characteristics influenced by selection in evolutionary biology.

Challenges to Natural Selection

  • Key issues to address in the study of evolution include:

    • Complex structures and their evolution.

    • The role of seemingly simple traits.

    • Mechanisms of inheritance and persistence of variation.

Basic Principles of Fitness

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