Change Through Time: Evolution

General Properties of Living Systems

  • Chemical uniqueness

  • Complexity and hierarchical organisation

  • Reproduction

  • Possession of genetic program

  • Metabolism

  • Development

  • Environmental interaction

  • Movement

  • Change over time

Evolution

  • Defined as change over time.

  • Key Contributors:

    • Charles Darwin: "The Origin of Species"

    • Jean-Baptist Lamarck: Transmutation of species

    • Alfred Russel Wallace: Similar evolutionary theory

    • Gregor Mendel: Traits inheritance

    • Watson and Crick: DNA structure

Types of Evolution

  • Microevolution: Small-scale changes within a lineage.

→ driven by natural selection

  • Macroevolution: Large-scale changes, involving origin & extinction of lineages. (create new species)

  • Evolution = change in allele frequency in a population. (evolution occurs in the population stage)

Species

  • Biological Species Concept: Group of interbreeding individuals, reproductively isolated from others.

  • Speciation: Creation of new species, often via geographical isolation (allopatric speciation).

Mechanism of Evolution

  • Evolution occurs at the population level.

  • Microevolution leads to macroevolution and speciation.

Theories of Darwinism

  1. Perpetual change

  2. Common descent

  3. Multiplication of species

  4. Gradualism

  5. Natural selection

Natural Selection Process

  • Variation exists in populations.

  • Overproduction leads to competition.

  • Selection favors adapted individuals; they reproduce and pass on traits.

Adaptation

  • A trait that enhances survival and reproduction; result of natural selection.

  • Adaptive radiation: evolution of diverse species from a common ancestor.

Evolutionary Mechanisms

  • Convergent evolution: Unrelated species evolve similar traits (e.g., shark, penguin, dolphin).

  • Other mechanisms: Random genetic drift, mutations, gene flow, non-random selection, sexual selection, and artificial selection.