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Speciation & Macroevolution. Species. What is a species?. Speciation. Microevolution – Speciation – Macroevolution. Reproductive Isolation. Reproductive isolation – Classified as: - Prezygotic mechanisms – - Postzygotic mechanisms –. 5 Prezygotic Mechanisms.

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Presentation Transcript

Species
Species

What is a species?


Speciation
Speciation

  • Microevolution –

  • Speciation –

  • Macroevolution


Reproductive isolation
Reproductive Isolation

  • Reproductive isolation –

    Classified as:

    - Prezygotic mechanisms –

    - Postzygotic mechanisms –


5 prezygotic mechanisms
5 Prezygotic Mechanisms

Groundhog – lives in fields at lower elevations

Marmot – lives in alpine meadows


Prezygotic mechanisms cont d
Prezygotic Mechanisms Cont’d

2.

Day and night-blooming cacti


Prezygotic mechanisms cont d1
Prezygotic Mechanisms Cont’d

  • 3.

  • 4.

Insects of a particular size and shape can enter the Pink Lady Slipper’s sac to get pollen


5 prezygotic mechanisms1
5 Prezygotic Mechanisms

5.

Coral reefs release sperm and egg. Those from same species will fuse together


3 postzygotic mechanisms
3 Postzygotic Mechanisms

Different species may produce a hybrid –

  • Zygotic mortality –

    2. Hybrid inviability –


3 postzygotic mechanisms1
3 Postzygotic Mechanisms

3.

+

horse

donkey

Mule - infertile


Modes of speciation
Modes of Speciation

Allopatric Speciation –


Modes of speciation1
Modes of Speciation

Sympatric Speciation –

Frogs live in same habitat – but 1 is diploid, other is tetraploid

What does that indicate about their evolutionary relationship?


Divergent evolution
Divergent Evolution

Divergent Evolution –


Convergent evolution
Convergent Evolution

Convergent Evolution –

Why would this occur?


Rates of evolution
Rates of Evolution

  • Theory of Punctuated Equilibrium –

    • - Species evolve drastically in rapid bursts of change (evolution time) followed by long periods of no change

    • - Transition fossils are rare

  • Theory of Gradualism –

    • - Many small changes accumulate over time to produce a different species

    • - Gradually become distinct from parent generation

    • - Transition fossils are common


Rates of evolution1
Rates of Evolution

Both theories are widely accepted


Co evolution
Co-evolution

Co-evolution –

Plants require bees to disperse pollen. To attract bees –produce sweet nectar


Plants and herbivorous insects
Plants and Herbivorous Insects

Monarch caterpillar tolerates milkweed’s toxins and can store it in its tissues to make itself poisonous to others



Does evolution always produce perfect organisms
Does Evolution Always Produce Perfect Organisms?

Any other examples we’ve discussed?


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