Notes species and speciation
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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

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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!


    Famous hybrids that are strong but sterile

    Famous Hybrids that are strong but STERILE!


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