The Process of Microevolution

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The Process of Microevolution

• Selection Directional, Stabilizing, and
  Disruptive Selection
• Microevolution vs. MacroevolutionMicroevolution
  change in allele frequencyMacroevolution
  formation of new species

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Microevolution

• The environment selects the best traits in the
  form of alleles that are advantageous for the
  given conditions
• i.e. the ability to digest a new food, or a new
  skin pigment may allow an organism to blend in
  with its environment
• Genotype genetic make-up, what alleles an
  organism has
• Phenotype appearance, what it looks like

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Examples of Microevolution

• Case 1 Galapagos Finch
• Case 2 English Pepper Moth
• Case 3 Mystery Predator
• Case 4 Human Blood Types
• The common denominator in each of these cases is
  the change in the alleles of a given gene or set
  of genes
• If there is a change in the frequency of the
  allele(s), then there will be a change in the
  genotype and phenotype of the population

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English Peppered Moth
Before industrial revolution After industrial
revolution
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M and Ms in the wild
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The M and M Predator

• Showing effects of different M M colors
  surviving over time

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Your turn!Be the chocolate predator

• Empty M and M bag on table.
• Place colors on matching dots.
• Place colors that dont match (green) wherever
  you have space.
• Now, EAT your M and M prey that dont match
  (easiest to find)

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M and M Population-Before Predation
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M and M Population-After Predation
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Microevolution effects on populations over time

• Life history patterns how species reproduce
• How successful each of the variations in species
  will be at reproducing
• Which M and Ms color will likely have a
  frequency change?

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Summary

• The environment is the selecting force that
  determines the best fit of traits.
• Positive and negative selecting pressures cause a
  shift in the of a trait in a population of a
  given species
• The changes result in genetic shuffling
• Eventually these gene shifts may be great enough
  to cause species to change

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Human Example

• Four Human Blood types-
• O is original
• A and B are two blood type changes resulting from
  dietary shifts and immune responses
• AB is newest, due to mixed A and B populations

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