Darwin’s Five Observations

  • More young are produced than survive
  • Individuals vary in their characteristics
  • Some characteristics are better than others
  • These characteristics are inheritable
  • Long periods of time are available

Darwin’s Two Major Points

  • Many species of organisms presently inhabiting the earth are descendants from ancestral species that were different from modern species
  • The mechanism he proposed for this was natural selection

Results of Natural Selection

  • Evolutionary adaptation: an accumulation of inherited characteristics that enhance an organisms ability to survive and reproduce in its environment
  • Evolution: the change over time in the genetic composition of a population

Definitions

  • Taxonomy: The branch of biology concerned with naming and classifying organisms
  • Classifying life: species > genus> family> order> class> phylum> kingdom> domain
  • Fossils: The remains of traces of organisms
  • Sedimentary rock: Formed from sand and mud that settles in seas, lakes and marshes
  • Paleontology: The study of fossils
  • Catastrophism: Each boundary between strata represents a catastrophe. Opposes idea of gradual evolution
  • Gradualism: The idea that profound change can take place through the cumulative effect of slow but continuous process
  • Uniformitarianism: The same geological processes are operating today as they did in the past
  • Population: The smallest unit that can evolve

The Origin of Species

Descent with modification: As descendants of ancestral organisms spilled into various habitats over millions of years, they accumulated diverse modification or adaptations that fit them into specific ways of life

Natural selection

  • Natural selection is the differential success in reproduction among individuals that vary in their heritable traits.
  • Over time, natural selection can increase the adaptation of organisms to their environment
  • If an environment changes, natural selection may result in adaptation to the new environment
  • Can amplify or diminish only heritable traits
  • Natural selection can distinguish between acquired traits and inherited traits

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