the origin of species chapter 24 the species problem modes of speciation the tempo of speciation...
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“It’s a liger”liger Slide 1 “bred for its skills and magic”TRANSCRIPT
The Origin of Species Chapter 24The Species Problem
Modes of Speciation The Tempo of Speciation
Gradualism Punctuated Equilibrium
Morphological
Ecological
Phylogenetic
Biological
Autopolyploidy
Polyploidy
Prezygotic Postzygotic
Reduced Hybrid fertility
Reduced Hybrid viability
Temporal
Gametic Hybrid breakdown
Behavioral
Mechanical
Allopolyploidy
Sympatric Allopatric
Habitat
CD Activity (old)
Are ligers a species?
“It’s a liger”
Hybrid Zones
Reinforcement
Fusion
Stability
Reproductive Isolation
Original Population
Allopatric SpeciationSympatric Speciation
Slide 1
“It’s a liger”
Slide 1
“bred for its skills and magic”
http://www.youtube.com/watch?v=CD6vpheUoPE
napoleon-dynamite-clip8.mov
Slide 1
Autopolyploid Speciation
Allows the formation of a new species from one parental plant.Step 1 Step 5Step 2 Step 6Step 3 Step 4
Note: Autopolyploid contains 2X the amount of Chromosomes than original species
Slide 1
Allopolyploid Speciation
Allows the formation of a new species of plant with starting with 2 different plants of different chromosome number
Step 1
Step 1 Step 2 Step 3
Note: Allopolyploid contains the sum total the chromosomes of the 2 parental species 4 + 6 + 10
The Gradualism Model of Evolution
The Punctuated Equilibrium Model of Evolution
Slide 1
Many slow changes over time form a new species
New species emerge quickly (punctuated) but change little over long periods (equilibrium)
Populations in different habitats do not interact
No attraction between males and females
Mating or flowering in different times
Sex organs structures prevent reproduction
Gametes fail to interact Fertilized
zygotes fail to develop
Hybrids do not make functional gametes
Hybrids have reduced health
Prezygotic Barriers Postzygotic Barriers
Temporal GameticBehavioral Mechanical HabitatReduced
Hybrid FertilityReduced
Hybrid ViabilityF2 Hybrid
Breakdown
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A. harrisi A. leucurus
Grand Canyon
Slide 1
North Rim South Rim
Strengthening reproductive barriers…hybrids cease to form
Weakening reproductive barriers…the 2 species fuse
Continued production of hybrid individuals
Possible Outcomes for Hybrids in a Hybrid Zone
Slide 1
Example of Reinforcement in Hybrid Zones
Slide 1