2/26/22
Sympatric Speciation: by polyploidy
•Gene flow in sympatry may be prevented by polyploidy
à Much less common in animals than plants
Mistake in mitosis
Mistake in
meiosis
Normal gamete
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75
Sympatric Speciation: by polyploidy
•Why does a mutation of polyploidy result in individuals that are
genetically isolated?
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2/26/22
Sympatric Speciation: by polyploidy
•How does polyploidy lead to reproductive isolation?
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How do polyploid individuals form?
•2 general mechanisms:
1. Autopolyploidy
Mistake in mitosis
Mistake in meiosis
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2/26/22
How do autopolyploid individuals result in speciation?
n gamete
+
2n gamete
3n zygote
(in) viable, sterile
= reproductive isolation of polyploid
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How do allopolyploid individuals form?
•2 general mechanisms:
2. Allopolyploidy
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2/26/22
Sympatric Speciation: by polyploidy
•Gene flow in sympatry may be prevented by polyploidy
à Much less common in animals than plants
Allopolyploidy
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OF YORK UNIVERSITY
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81
Sympatric Speciation: by polyploidy
• Much less common in animals than plants
NOT FOR SALE
OR DISTRIBUTION PROPERTY OF YORK UNIVERSITY
Allopolyploidy
Autopolyploidy
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2/26/22
Sympatric speciation by polyploidy – more
common in plants than animals
•Why plants speciated more by polyploidization than animals?
1. Reproductive cells in plants not separated early in
development.
2. Ability of some to self-fertilize
3. Hybridization b/w spp is common (creates opportunities for speciation
via formation of allopolyploids)
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Chromosome rearrangements/changes can alter gene
regulation
Humans 2n = 46
Chimpanzees, gorillas, orangutans 2n = 48
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