Evidence for Evolution

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Evidence for Evolution

• One of the major ways in which scientists can
  observe evolution is by looking at small-scale
  evolutionary phenomena.
• This is known as microevolution.
• Microevolution describes changes that occur
  within a population of a single species.

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• Peppered moth
• the peppered moth has undergone a change in its
  population genetics because of human
  interference.
• Studied in England.
• Industrial melanism to refers to the genetic
  darkening of species in response to pollutants.

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2. Drug resistant bacteria

• Example penicillin
• - a wonder drug of the 50s it helped cure many
  ailments
• - because of over-prescription and abuse by
  patients many new mutated forms of bacteria are
  emerging that are antibiotic resistant

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Weak forms destroyed
Application of antibiotics
Dish with bacterial cultures
Increased dosage
Isolation of resistant bacterial strains
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3. Insecticide Resistance

• DDT was a lethal form of insecticide to all
  insects in 1950s but today 225 species are
  resistant.
• One actually uses it for a food source.

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New Frog Species!
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More Evidence for Evolution

• Macroevolution - refers to large scale and
  long-term evolutionary patterns among many
  species.
• Macroevolution cannot be studied directly.
• It is studied by examining patterns in biological
• populations and groups of related organisms
  and inferring process from pattern.

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1. The Number of Species

• There are numerous amounts of species that are
  very similar in their appearance and in the
  biological niche they occupy.
• These similar animals are modified depending on
  the area in which they live.
• Example Darwins Finches

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2. Biogeography

• The distribution of plants and animals in the
  various regions in the world.
• Examples
• Why are marsupials found in Australia and not
  elsewhere?
• Why are similar organisms found on coastal
  shorelines of similar islands?

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• As Pangea split 220 million years ago mammals
  were evolving.
• Australia split from the supercontinent early and
  it is believed that the ancestor to marsupials
  was found there.
• elsewhere they were outcompeted.

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3. The Fossil Record

• Reveals a succession of living forms, with
  simpler forms generally preceding more complex
  forms.
• Fossil - any remains, trace, or imprint of a
  plant or animal that has been preserved in the
  earths crust since some past geologic or
  prehistoric time.

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Transitional Fossils

• is the fossil remains of a creature that exhibits
  certain primitive traits in comparison with its
  more derived descendants.
• Otherwise known as a Missing Link.

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Example Archaeopteryx
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4. Comparative Anatomy

• Homologous Structures
• Similar structures across species due to common
  descent, irrespective of the diverse uses to
  which they may be put.

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Example Pentadactyl Forelimb
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• Opposed to homologous structures are analogous
  structures.
• Analogous structures have similar appearance and
  function, but have evolved from entirely
  different backgrounds.
• Often a result of convergent evolution.
• Example
• - Birds wings/insects wings
• - Shark fins/whale fins

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Convergent Evolution
Placental mammals top row Marsupial mammals
bottom row
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5. Embryology

• Embryos of mammals all possess a notochord (stiff
  dorsal rod), gill slits, seven cervical
  vertebrae, and four limbs.

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6. Vestigial Structures

• Organs or appendages that are no longer of use,
  but remain as remnants of evolutionary past.
• Examples - Pelvic bones in whales and snakes
• - Male nipples
• - appendix

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7. Molecular Biology

• Sequencing of DNA and proteins indicates the
  degree of relatedness between organisms.