Speciation

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Speciation

• Ch 14

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What is a species

• Numerous definitions
• Biological Species Concept
• Morphological Species Concept
• Ecological Species Concept
• Phylogenic Species Concept

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Evolutionary Theories
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Creating a Species

• Reproductive Isolation
• Reproductive Barriers
• Prezygotic Barriers
• Postzygotic Barriers

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Prezygotic Barriers

• Temporal Isolation
• Habitat Isolation
• Behavioral Isolation
• Mechanical Isolation
• Gametic Isolation

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Postzygotic Barriers

• Reduced Hybrid Viability
• Reduced Hybrid Fertality
• Hybrid Breakdown

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Speciation

• Emergence of a new species
• Allopatric vs Sympatric
• Creation of reproductive barriers

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Sympatric Speciation

• Niche separation, sexual selection, habitat
  differentiation
• Polyploid

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2
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Self- fertilization
Parent species 2n 6
Tetraploid cells 4n 12
Viable, fertile tetraploid species 4n 12
Diploid gametes 2n 6
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Sympatric Speciation

• Hybrid Polypoid

Chromosomes not homologous (cannot pair)
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2
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Gamete n 2
Species A 2n 4
Sterile hybrid n 5
Viable, fertile hybrid species 2n 10
Gamete n 3
Species B 2n 6
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Hybrid Zones

• Regions where different species meet and mate
• Outcomes
• Reinforcement
• Fusion
• Stability

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Adaptive Radiation

• Evolution of diverse species from common ancestor
• Colonization
• Extinctions

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• http//www.youtube.com/watch?vYCoEiLOV8jc
• http//www.youtube.com/watch?vv9i2WYS60L4