Speciation WebVista

Speciation WebVista - Sympatric Speciation(ss Changes in...

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Speciation Chapter 16
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Definition of Species Species –   Biological species concept – Limitations of concept 
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Appearances Misleading Myrlte warbler and  Audubon’s warbler-2  species in 1970’s with  different geographical  ranges  Actually, local varieties of  the same species
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How do New Species Form? Speciation –  Ernst Mayr –speciation depends on 2  factors acting on a pair of populations:
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Isolation of Populations 2 populations cannot grow increasingly  different Speciation
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Genetic Divergence of Populations Not sufficient for 2 populations to be isolated. Become separate species, 
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How Genetic Difference Arise Genetic Drift  Natural selection – 
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Mechanisms for the Origin of New Species Allopatric Speciation  –  2 populations Sympatric Speciation  –  2 populations
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Allopatric Speciation Geographical  isolation-    Continental drift,  chasm, river
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Sympatric Speciation Ecological isolation-  populations  Habitat differences  Ex: Darwin’s finches
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Unformatted text preview: Sympatric Speciation (ss) Changes in chromosomes lead to ss Change in number of chromosomes = Polyploidy – Animals-Changes within a Species Cause Speciation Mechanisms of speciation & reproductive isolation Adaptive Radiation Ex cichlid fish How is Reproductive Isolation Maintained? Isolating Mechanism – Premating Isolating Mechanisms – Postmating Isolating Mechanisms – Premating Isolating Mechanisms Geographical Isolation-Fig Wasp Temporal Isolation - Pines Mechanical Incompatibilities – songbirds Postmating Isolating Mechanisms Gametic Incompatibility- Hybrid Inviability Hybrid Infertility- Ex: horse x donkey = mule Liger Tigon What Is Extinction? Extinction 99.9% of all species that have ever existed are now extinct. Causes of Extinction Death of all members of a species Causes of Extinction...
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This note was uploaded on 02/01/2011 for the course BIOLOGY 1104 taught by Professor Dr.dianeday during the Summer '10 term at Georgia State.

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Speciation WebVista - Sympatric Speciation(ss Changes in...

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