Evolution

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Evolution

• Change in inherited traits due to beneficial DNA
  mutations leading to the formation of new
  species.
• Results in a change in the gene source
• Theory introduced by Charles Darwin
• 1859 On the Origin of Species by
• Means of Natural Selection

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Charles Darwin

• Influenced by Charles Lyells Principles of
  Geology suggesting fossils found in rocks are
  evidence of organisms that lived thousands or
  millions of years ago.
• Darwin observed variety in animal life and
  geological features (Galapagos Islands) made
  connections to Lyells theories
• Realized natural forces gradually change Earths
  surface and those forces still occur in modern
  times (geological evolution)

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Charles Darwin History

• Joined the H.M.S. Beagle (1831-1836) as a
  naturalist to survey the south seas (South
  America and the Galapagos Islands) collecting
  plant and animal samples
• On the Galapagos Islands, he observed species
  that lived no where else in the world.

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Darwins Principles of Natural Selection

• Organisms produce more offspring than can survive
• Variations occur among individuals of a species
• Genetic variations are passed on to offspring
• Organisms with helpful variations survive and
  reproduce while others do not
• Over time, offspring of individuals with helpful
  variations make up more of a population and may
  become a separate species

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Natural Selection

• Individuals with favorable traits
• are more likely to survive,
• reproduce, produce offspring
• suited for survival in their
• environment.
• Example
• English peppered moth (Biston
• betularia) and the industrial
• revolution

Try out this simulation w/ the peppered
moths http//www.biologycorner.com/worksheets/pep
peredmoth.html
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Artificial Selection

• The selective breeding of domesticated plants and
  animals occurs in Darwins time making it
  possible to see first hand how variations in
  traits could be formed and passed on in animal
  populations such as dogs, sheep, and cattle

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Evidence of Evolution

• Biogeography
• Geographical
• distribution of species

• 2. Fossil Record order in which
• fossils appear in layers of
• sedimentary rock shows
• evolutionary history

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Evidence of Evolution

• 3. Taxonomy classification
• of life forms based on
• similarities differences

4. Homologous structures similar structures
which come from a common ancestor
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Evidence of Evolution

• 5. Comparative embryology
• Study of structures that appear
• during embryonic development.

6. Molecular biology DNA and proteins
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Interpretations of time

• 1. Gradualism Slow changes in species overtime

2. Punctuated Equilibrium Evolution occurs in
relatively rapid change
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Adaptive Radiation

• Emergence of numerous species derived from a
  common ancestor introduced to new environments.
• Example
• Darwins Finches

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Convergent Evolution

• Species
• from different
• evolutionary
• branches may
• come to resemble
• one another if they
• live in similar
• environments

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Coevolution

• Evolutionary change, one species acts as a force
  influencing the adaptations of a second species

Example Humming birds plants with tube-like
flowers hummingbird selects these flowers thus
their pollen is spread and the flowers survive to
pass on their genes
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Macroevolution

• Taxonomic groups higher than the species
• level

Microevolution
A change in a populations gene pool over
generations. Evolutionary changes in species over
relatively brief periods of geological time.
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Causes of Microevolution

• 1. Genetic drift Change in the gene pool of a
  small population due to chance.

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Genetic DriftBottleneck Effect

• Genetic drift (reduction of alleles in a
  population) results from disaster that
  drastically reduces the population size.
• Examples
• 1. Earthquakes
• 2. Volcanos

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Genetic DriftFounder Effect

• Genetic drift resulting from the colonization in
  a
• new location by a small number of individuals
• Which results in random change of the gene pool
• Example
• 1. Islands

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Causes of Microevolution cont.

• Gene Flow gain or loss of alleles from
• a population by movement of individuals

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Causes of Microevolution cont.

• 3. Mutation Change in an organisms DNA
  creating a new allele
• Non-random mating selection of
• mates other than by chance
• 5. Natural selection Differential reproduction