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Notes: SPECIES and SPECIATION. Species - A group of similar organisms Can breed with each other and produce fertile offspring Examples: Human species ( Homo sapiens) Horses and donkeys = two separate species because their offspring (mules) aren’t fertile. Objectives for Class:

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notes species and speciation
Notes: SPECIES and SPECIATION

Species -

  • A group of similar organisms
  • Can breed with each other and produce fertile offspring

Examples:

  • Human species (Homo sapiens)
  • Horses and donkeys = two separate species because their offspring (mules) aren’t fertile
  • Objectives for Class:
    • Explain the defining characteristics of a species
    • Describe the 2 steps of speciation
speciation
Speciation -
  • The formation of new species from a common ancestor
  • The gene pools of two populations must become separated

Ex: The Galapagos Finches

  • Objectives for Class:
    • Explain the defining characteristics of a species
    • Describe the 2 steps of speciation
two main steps of speciation
Two Main Steps of Speciation
  • Reproductive Isolation
  • Changes in the Gene Pool
      • Gene Pools Diverge (become different)
      • Genetic Barriers to Reproduction Arise (groups can’t interbreed and make fertile offspring)
  • Objectives for Class:
    • Explain the defining characteristics of a species
    • Describe the 2 steps of speciation
step 1 reproductive isolation
Step 1: Reproductive Isolation

One population becomes separated and stops breeding with the rest of the species

a) Geographic

  • Geographic barrier splits population (i.e.: river, mountain, body of water, etc.)
  • Populations are separated and cannot interbreed

b) Behavior:

  • Changes in courtship or other reproductive strategies

c) Temporal

  • Species reproduce at different times or have other behavior that becomes time sensitive (i.e.: feeding)
  • Objectives for Class:
    • Explain the defining characteristics of a species
    • Describe the 2 steps of speciation
step 2 changes in the gene pool
Step 2: Changes in the Gene Pool
  • Gene Pools Diverge (become different):
      • The isolated populations become genetically different.
      • The new environments or behaviors favor different genetic traits (natural selection)
  • Genetic Barriers to Reproduction Arise
      • The two populations can no longer interbreed
      • Due to genetic differences in habitat preference, mating behavior, or physical compatibility

They are now two separate species!

  • Objectives for Class:
    • Explain the defining characteristics of a species
    • Describe the 2 steps of speciation
hybrid
Hybrid -
  • The offspring of a mating between two different species
  • If a hybrid can’t have offspring, there are still two separate species!
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