CO2

• Evolution

  1. Modern organisms have descended from ancient ancestors

  2. Changes in genetic composition (traits) of species in population over time

  3. Only occurs when there is a change in gene frequency and genetic variation
• Causes of Genetic Variation

  • MUTATION: Change in specific sequences of nucleotides in DNA
  • MIGRATION: Gene flow, Movement of individuals or species or populations from one area to another, Caused by migration and interbreeding
  • GENETIC DRIFT: Change in gene frequency due to chance, FOUNDER EFFECT: A small group of individuals isolated from a larger population, Caused by migration and genetic drift, Example: Aeta Population in the Philippines, BOTTLENECK EFFECT: An example of genetic drift that happens when the size of a population is severely reduced due to sudden change in environment and/or natural disasters, Example: Philippine tamaraw (Bubalus mindorensis)
• Adaptation


  • A process which enables organisms to adjust to their environment in order to ensure survival
• Sexual Selection

  • Intersexual Selection: Members of biological sex choose mates of the other sex to mate with, "between-sex", Intrasexual Selection: Compete with members of the same sex for access to members of the opposite sex, "within-sex"
• Development of Evolutionary Thought

  Aristotle: Developed the concept of "Scala Naturae" (The Great Chain of Being), Categorized organisms into hierarchy based on perceived complexity
• Evolution Keywords

  • DESCENT WITH MODIFICATION: Species evolve from common ancestors, gradually changing over time as traits are passed from one generation to the next
  • GENE FREQUENCY: Allele frequency, Frequency of an allele within a population, Frequency of different alleles changes in response to changing environment; frequency of the advantageous allele increases in the population
  • GENETIC VARIATION: Presence of differences in sequences of gene between individual organisms of species, Allows adaptation to occur, Increases the survival rate of species
• Artificial Selection

  • Ancient method of genetic engineering to cause major changes in the features of an organism, Humans (instead of nature) select which organisms with desirable characteristics get to reproduce causing evolution
• Patterns of Descent with Modification

  DESCENT WITH MODIFICATION: Fundamental concept of evolution, Related to heredity, Genetic variation
• Natural Selection

  • Process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype or genetic composition, "Survival of the Fittest", Example: Philippine Eagle (Pithecophaga jefferyi), FITNESS: Describe how good a trait is to be present in a species in the next generation, Ability to survive, Find a mate, Produce an offspring, Leave fit genes in the next generation
• Lamarck's Theory

  • Inheritance of Acquired Traits: Organisms pass on traits acquired during their lifetimes
  • Principle of Use and Disuse: Organism's use or disuse of certain organs lead to modification or disappearance over time
• Development of Evolutionary Thought

  • Aristotle developed the concept of "Scala Naturae" (The Great Chain of Being)
  • Baron Georges Cuvier is the Father of Paleontology and did not support evolution
  • Jean-Baptiste de Lamarck proposed the Inheritance of Acquired Traits and the Principle of Use and Disuse
  • James Hutton proposed the Theory of Slow, Uniform Geological Change
  • Charles Lyell proposed the Theory of Uniformitarianism
  • Thomas Robert Malthus wrote "An Essay on the Principle of Population" about the struggle for existence
  • Carolus Linnaeus is the Father of Taxonomy
• Lyell's Theory


  • Theory of Uniformitarianism: Geological processes occur gradually and uniformly over vast spans of time
• Linnaeus's Contribution

  • Developed a hierarchical system of classifying life's diversity based on anatomy and morphology
• Galapagos Island's Tortoises

  • Dome Shaped: Short neck, domed shell; found in areas with high vegetation
  • Saddleback: Long neck, curved shell; found in dry islands
• Descent with Modification

  • Fundamental concept of evolution
  • Related to heredity
  • Genetic variation
• Hutton's Theory


  • Theory of Slow, Uniform Geological Change: Geological processes occur gradually and uniformly over vast spans of time
• Cuvier's Theory of Catastrophism

  • Suggests that Earth's history was marked by sudden, catastrophic events leading to extinction and appearance of new species
• Charles Darwin's Expedition

  • 1831: 5-year expedition to South America via HMS Beagle Ship
  • Collected and studied plant and animal specimens, bones, and fossils
  • Notable stop: Galapagos Islands
• Malthus's Theory

  • An Essay on the Principle of Population: Human populations grow exponentially leading to a struggle for existence
• Alfred Russel Wallace


  • British naturalist, explorer, and biologist who arrived at similar conclusions regarding evolution independently
• Key Components of Darwin-Wallace Theory of Natural Selection

  • Genetic Variation
  • Struggle for Existence
  • Survival of the Fittest
  • Adaptation & Evolution
• Alfred Russel Wallace: 'British naturalist, explorer, and biologist who worked independently, arrived at similar conclusions regarding natural selection and evolution'
• Dome Shaped Tortoises


  • Short neck, domed shell; found in areas with high vegetation
• Divergent Evolution

  • Two or more species evolved (diverged) from a common ancestor
• Direct Observation

  Evidence of small-scale evolutionary changes directly observed in an organism with short life cycles
• Homology

  • Homologous Structures
  • Embryonic Homologies
  • Vestigial Structures
  • Molecular Homologies
• Modes of Speciation

  • Allopatric Speciation
  • Habitat Isolation
  • Temporal Isolation
  • Behavioral Isolation
  • Sympatric Speciation
• Species

  • Defined as a group of population whose members can interbreed naturally and produce viable, fertile offspring
• Alfred Russel Wallace

  1. Studied wildlife in the Amazon and Malay archipelago

  2. Published a paper outlining evolution by natural selection (1858)
• Galapagos Island’s Tortoises

  • Dome Shaped
  • Saddleback
• CO2: Evolution: Evidence for Evolution

  • Microevolution
  • Macroevolution
• Saddleback Tortoises


  • Long neck, curved shell; found in dry islands
• Fossil Records

  1. Relative Dating

  2. Radiometric Dating

  3. Both are used to date fossils and determine age
• Convergent Evolution

  • Two or more distinct species share a common trait not due to a common ancestor
• Speciation

  • Evolutionary process by which populations evolve and new species arise
  • Can take place with or without geographic separation
• Biogeography

  Scientific study of geographic distribution of organisms