BIO112 Chapter 22: The Evidence for Evolution

Chapter 22: The Evidence for Evolution

Learning Objectives

  • Understand the environment impacting the Theory of Evolution.

  • Discuss Charles Darwin's journey to the Theory of Evolution.

  • Review evidence supporting the Theory of Evolution.

  • Explore molecular mechanisms influencing evolution.

Definition of Evolution

  • Biological evolution: changes in population characteristics over generations.

  • Changes inherited through genetics.

  • Environmental factors can cause non-genetic changes.

Key Concepts

  • Evolution occurs in populations, not individuals.

  • Natural Selection: differential survival and reproduction based on traits.

    • Examples: pesticide resistance, antibiotic resistance.

  • Microevolution: small changes within a species.

  • Macroevolution: large-scale changes leading to new species.

Historical Perspective

  • 1600s: John Ray develops early species concept.

  • 1700s: ideas of species change proposed by Buffon and Lamarck (inheritance of acquired characteristics).

  • Darwin's background: theology and natural sciences, voyage on the HMS Beagle.

Influences on Darwin

  • Reading Principles of Geology (Earth's old age).

  • Population growth essays (resource limitations).

Timeline Development of Evolution Theory

  • Darwin's observations led to the theory in the 1840s.

  • Papers published in 1858, followed by "The Origin of Species" in 1859.

Determinants of Evolution

  • Requires variation in populations.

  • Mechanism for trait inheritance.

  • Time: Earth is approximately 4.6 billion years old.

Evidence for Evolution

  • Anatomical similarities (homology).

  • Vestigial traits.

  • Developmental pathways.

  • DNA similarities among species indicate common ancestry.

  • Experimental evidence, e.g., E. coli cultures evolved to digest citrate.

  • Artificial selection provides insight into natural selection mechanisms.

Molecular Processes

  • Homologous genes and their roles in evolution.

  • Horizontal gene transfer among organisms.

  • Chromosomal changes reflect evolutionary relationships.

Biogeography

  • Geographic distribution influences species evolution (island species vs. mainland).

  • Fossil evidence supports historical changes in species due to continental drift.

Fossils and Dating Techniques

  • Radiometric dating establishes the age of fossils.

  • Transitional forms like Tiktaalik illustrate evolutionary links between groups.

Summary

  • Evolution is supported by diverse evidence including genetic, anatomical, and fossil records.

  • Natural selection is a driving force behind evolution, requiring variations and a long timescale for significant changes.